Note: UL means ultralight. There is a trend among backpackers to carry gear as light as possible.
Note II: Always look for gear at a discount. Steep and Cheap is my favorite, but you can get almost any piece of gear for a discount. Just because someone has a pack full of nice new gear doesn't mean they shelled out for it.
Note III: There is almost never an end all, be all for any single piece of gear. See what fits for your style and budget. These are simply my observations and opinions.
Pack - Granite Gear / VC Crown 60 (2lb 2oz)
Your pack needs to do two things. It should hold your stuff and ride comfortably. That's about it. That's exactly what the Crown 60 does, and it does it well. It does not have tons of bells and whistles, but it doesn't need to. It's comfy, light and reliable. One of my favorite pieces of gear. If it has a shortcoming, it's the lack of hip-belt pockets, but you can buy them and add them if you like. A very popular pack this year.
Sleeping bag - North Face / Blue Kazoo (2lb 6oz)
My sleeping bag is slightly heavier than average, but not by too much. It kept me warm almost every night but the most bitter cold and did so at a cost that was impossible to pass up. Not the fanciest piece of gear I own, but certainly one of the best values.
Sleeping pad - Thermarest / Prolite 4 (1lb 8oz)
My pad is an inflatable one, so you have to blow it up. Not a big deal, since it is one of the more comfortable options out there. It doesn't pack down as small as other pads, nor is it as light as most others, but it performs well and was cheap.
Also consider: Thermarest / Neo Air , the Cadillac of sleeping pads. Expensive, but the most comfortable and definitely UL. Requires lots of blowing up. Were I to do the trail again, I'd get this in a 3/4 length and use my pack for under my feet. (8oz for the shorty)
Also: Thermarest / Z-lite. Very popular, UL, durable and inexpensive. Doubles as a sit pad. Not exactly the cushiest pad though. (10oz for the shorty)
Groundsheet - 2' x 7' sheet of Tyvek (4oz?)
Totally necessary. I bought mine for $5, it weighs next to nothing, adds mild insulation and protects both your tent and sleeping pad from punctures and abrasions.
Tent - Easton / Kilo 1p (1lb 14oz)
I loved my tent. It's light, reliable, kept me warm and dry, has a decent size vestibule, and doesn't take too long to set up. Add the great price at which I purchased it, and it is a great buy. The big downside was that it is a monopole tent and, therefore, not freestanding, which means you have to be careful how you set it up in the wind, but that was never really a problem for me. Unfortunately nobody seems to have it in stock anymore.
Also consider: Big Agnes / Flycreek UL 2, a very popular tent on trail and with good reason. (1lb 15oz)
Don't consider: Tarptent / Contrail. Everyone I knew who had one if these hated it.
Headlamp - Petzl / Tikka XP 2 (3oz)
While the headlamp can be a pretty inconsequential piece of gear, I loved mine. Bright/dim, beam/diffused, white/red lights. It's got all the features and doesn't weigh much.
Also consider: I can't be bothered to care.
Knife/multitool - Leatherman / Style CS Multitool (1.4oz)
Great little tool. Not too heavy and just the right tools, which include a knife, scissors, clip/bottle opener and a file.
These worked well for the desert and Sierra, but their effectiveness dropped off rapidly by time we hit dense forest in NorCal and Oregon. Useless in Washington. Plus, they aren't exactly UL, especially not with the Guide 10 attached.
At only $20 and and 5 ounces, I think this is a much better option for recharging your phone. It'll give my iPhone two charges, which should be enough for pretty much any section of the trail. It's also much smaller and less cumbersome than dealing with a solar panel.
Trekking Poles - Black Diamond / Ultra Distance Z-poles (10oz)
These are among the lightest poles available on the market and worked well for me. One broke, but Black Diamond had great customer service and immediately replaced it. Poles are actually one of the few pieces of gear where weight doesn't seem to matter so much. Even the need for having poles is up for argument. The lighter your pack, the less necessary they are. Sometimes I wouldn't use them for most of a section and find them irritating, especially over rocky terrain. Other times I found them invaluable. Mostly, I recommend looking for a pair that's affordable.
Stove - JetBoil / Flash (15oz)
The JetBoil is faster than anything else out there, but it's really only effective for boiling water. If you try to cook pasta and stuff in it you're going to burn stuff to the bottom, which is a major pain in the butt to clean. It's also slightly heavier than other options. If you cook a lot of Mountain House, Ramen or instant potatoes, though, it's awesome.
Nothing is going to be perfect, but this setup allows for actual cooking if you have things like Knorr sides or Mac'n'cheese. Not as fast as a JetBoil, but it's a little more versatile and lighter. Remember, variety is key when it comes to eating on the PCT.
A small one for odds and ends like toothbrush, permits and Ibuprofen. Also for sleep clothes. You could honestly just use a gallon ziplock bag though. Why didn't I think of that while I was still on trail
This shirt made the hike as awesome as it was. I bought it the day before we left and it's the best purchase possible. Breast pockets, a collar to look less trashy in town, durable fabric and sleeves that roll and button up make this shirt the ideal hiking top. The brand and model don't matter. You can find those features in a shirt from any brand, but dammit get a hiking shirt.
I can't begin to care. If you must know, I did the desert in 3/4 capris, the Sierra through Oregon in running shorts and eventually ditched those to only wear compression shorts on bottom.
Compression shorts - Under Armour
Underwear - Ex Officio / Give-n-go boxer brief
BEST. UNDERWEAR. EVER. I wore them the whole trail and they still look brand new. Hell, I even shit my pants once on trail and I'd wear the same pair for another thru-hike.
Sleep shirt - Under Armour / Cold Gear compression shirt
Nice and warm. Long sleeve sleep clothes are also good for keeping your disgusting skin from touching your sleeping bag. This helps keep your bag cleaner for longer. Mine might have been a bit heavy.
Also consider: Icebreaker long underwear. Like SmartWool's merino wool products, they are not cheap, but they are incredibly light and super comfy.
Sleep pants - SmartWool / Microweight long underwear
Merino wool is kind of expensive, but it's great quality. Lightweight, warm and very comfortable. Most any tights will do I guess.
Injinjis, Darn Toughs, Wigwams, Stoics and Balegas all worked well for me. Darn Toughs and Stoics were the best. I like the lighter weight running socks as opposed to the thicker, taller hiking socks.
Smartwool can suck it. Instant holes.
They can't make your hike, but they can break it. My feet swelled a size and a half almost instantly. I like my shoes light and with a wide toe box. Don't wear boots. Trail runners are the way to go.
Way too narrow for my feet and those of most hikers.
The most popular shoe on trails. Solid shoe. Decently wide and wears well. A great go-to. Highly recommended.
Wide toe box and great fit for my foot. Another bonus: they have Velcro for gaiters built in, in case gaiters are your thing. They are for me. Note: these shoes are zero drop and can require a little getting used to. Perhaps not as well suited for the Sierra Nevada or Washington sections. They wore out way faster over rough mountain terrain.
Gaiters - Dirty Girl
I really loved having gaiters. What kind you have doesn't matter, but the variety of designs Dirty Girl offers is cool. Not everyone likes them, but I found them great for keeping large amounts of sand and rocks out of my shoe. Yes, you're feet will still get filthy, and sand will still get in your shoes, though it won't be as bad as it would be otherwise.
Outdoor Research Gaiters
Pretty much the same as dirty girls, but plain looking.
Jacket - Mountain Hardwear / Ghost Whisperer (7oz)
This is hands down my favorite piece of gear. It's so light, so comfy and so warm. Not cheap, but I love it. As always, respect down and keep it dry.
Rain Jacket - Outdor Research / Proverb (13oz)
A solid rain jacket that was neither too expensive nor heavy. Not exactly the most breathable, but what good rain jacket is? There are lighter option out there, but I can't speak for how water resistant they are.
Also consider: Outdoor Research / Helium 2. It's lighter than mine.
Rain pants - Mountain Hardwear / Alkane Pant (9oz)
Great pants. Only really needed them for the Sierra and Washington, but boy were they great in Washington. The zipper up the side makes them easy to get on and off even with shoes on, they're very water resistant and surprisingly breathable for rain pants.
Warm hat - Outdoor Research / WinterTrek Fleece Hat
It was a nice, warm hat. Plus it had a wind-stopper in it.
Gloves - Seirus / Soundtouch hyperlite
Only really used them in the Sierra, but they work just fine. For the rest of the trail I used a pair of Injinji socks that I cut up into hobo gloves. Very hiker trashy, but they worked. I thought the ability to use my phone was going to be nice, which is why I got these gloves. Were I to do it again, I'd get some lightweight liner gloves that are easier to get on/off.
Yup. Preferably polarized. You WILL lose or break at least one pair on the trail.
As someone who had never really hiked before, it's a nice primer for the PCT and lightweight hiking. The 'book' section of the guide helps you figure out if this trail is really for you. The 'trail guide' section is a nice supplement to Halfmile while you're actually hiking. It's by no means necessary, but I don't regret buying it. Remember to hike your own hike (HYOH) and not simply follow Yogi though.
I personally didn't use Halfmile maps, but they are great if you are a visual person who likes to see topo maps. The elevation profiles at the end of each section are the best. They're free to download, but you still have to print them.
Indispensable. This was the No. 1 way for me to get trail data. You get distances and up/down to pretty much anything on trail, especially towns and water. It doesn't do everything, but the features it does have work very well. Free. Available for iPhone and Android.
At $6 per section ($30 total), I found the Guthook apps a useful and worthwhile companion to Halfmile's app. I did most of my navigation via iPhone, and Guthook was helpful as a map and for finding campsite locations. Available for iPhone and Android.
Smart Water bottle and wide mouthed Gatorade bottle.
Smart Water bottles are great because they use space well on the side pockets of your pack since they are tall and slender. They are less fussy to get in and out while you're walking too. Having one wide-mouthed bottle was handy for putting in drink mixes like Crystal Light or Nuun tablets. Each of these are lighter than your heavy duty bottles like a Nalgene. You will get laughed at if you carry a Nalgene. They're so heavy.
Platypus / SoftBottle 1L (1.4 oz)
During the desert you may need to carry five liters of water at any given time. During certain sections, you may even need to cary six (coming out of Tehachapi, Hat Creek Rim and leaving Crater Lake). It's nice to have an extra liter or two of storage that is compressible when you're not using it. This is a great choice and pretty much everybody uses them.
You mix seven drops from two different bottles, wait five minutes, put it in your water and then wait another 20 minutes. I loved these for the desert where we would get three to five liters at a time, but found them a bit more tedious for the rest of the trail where you only need to get between one and three liters at a time. I didn't notice much of a taste either.
Sawyer / Squeeze (3oz)
The plus side of the Sawyer is that it fits on a SmartWater bottle. You can fill up your bottle and drink straight from the bottle with the Sawyer on it, if that's your thing. Also, it filters out debris that you might have picked up your water. Otherwise, I found the Sawyer to be slow and inconvenient. I didn't use it much and we ended up sending it home.
Regular, unscented bleach. Two drops per liter. Wait half an hour and you're good to go. I switched to bleach somewhere in NorCal and never regretted it. Just don't add too many drops or it'll taste terrible and can destroy your stomach lining.