Gear I most frequently saw on the PCT in 2016, with notes. All of these items have gotten good reviews and would serve reliably on a thru-hike. If you don't want to do much research you could just go with these. I've also listed what I think are good alternatives, with associated tradeoffs.
Backpack: ULA Circuit
Probably the most tested pack on the trail, it's been a PCT standard for years. Fits a wide range of body types. Not the lightest thing, arguably not even "ultralight" today, but lighter than most packs you'd find of similar volume at REI. Also, not waterproof. Use a packliner (trash compactor bag) instead of pack cover, since the latter doesn't block water that seeps down your back. Probably too large if you're fast, stoveless, or using a single-wall shelter. Large hip belt pockets, enough to store snacks for an entire day of hiking. Mine looks like it could handle at least another thru-hike. It employs a carbon fiber frame and should be handled with care (no dropping it, or throwing it out of car windows)
Alternatives: Hyperlite Mountain Gear, more expensive lighter, waterproof, smaller hip belt pockets. ULA Ohm 2.0, smaller, lighter, a good choice for faster hikers or those going stoveless or bringing a single-wall shelter, cases in which the Circuit will probably be too big.
Shelter: Big Agnes Fly Creek UL1
A little cramped for taller people. Often seen patched up with Tenacious Tape, seemed to use thin fabric. Very light, pitches fast.
Alternatives: Big Agnes Copper Spur UL1 is larger, tougher.
Sleeping Quilt: Enlightened Equipment 20°F (various models)
The delicate fabric absorbs water readily, but this is not a major concern for the mostly fair-weather PCT. Really good quilt. Can be sized by length and width to save weight. Definitely go for the hydrophobic down.
Alternatives: Feathered Friends bags are heavier but use tougher, more water resistant fabric (Pertex). Could definitely be used in wetter conditions, like Cascade hiking in shoulder seasons. ZPacks also makes some well-regarded quilts.
Sleeping Pad: Therm‑a‑Rest NeoAir XLite
Many people used these the whole trip, including the desert. I never got punctures, but my experience seemed to be the exception and not the norm. Annoying to roll up in the morning. Really comfy and light though, I usually slept with it deflated 30% as a side sleeper.
Alternatives: Therm-a-Rest Z-Lite, quick folding, never deflates, the foam does compress after a while and lose insulating ability, and not so comfortable for side sleepers. The Therm-a-Rest NeoAir Xtherm is REALLY warm and suitable for snow, but some people really appreciated it for very cold ground in Oregon and Washington (this may be particular to the 2016 season).
Warm Jacket: Mountain Hardwear Ghost Whisperer
Pricy but often found on sale. Mine lost a lot of loft because I used it as a pillow, so don't do that (washing it revived it). Fabric feels fragile but there was surprisingly little wear after my thru-hike. Almost everyone preferred getting it with the hood to keep your head and neck warm.
Alternatives: Patagonia Nano-Puff is cheaper, synthetic and thus retains more warmth while wet, but has an inferior warmth/weight ratio.
Shoes: Altra Lone Peak 3.0
The PCT shoe these days. Should last 600-800 miles (one hiker reported 1,100 miles) depending on terrain, with small tears (still keep out most rocks) appearing in the forefoot at 400 miles or so. Tread held up really well. Lugs wore down evenly and never ripped off, I was seriously impressed by the treadwear. Most people wore these with Superfeet insoles and Dirty Girl Gaiters.
Alternatives: Brooks Cascadia is narrower, heavier, with more cushion. Altra Olympus has more cushion, also probably heavier.
Ice Axe: Camp Corsa
Incredibly light. I used my BD Raven Pro and regret it due to its weight. You're carrying so much in the Sierra Nevada that the half-pound I could have saved using the Corsa would have been welcome relief. Readily eBayable after the hike.
Alternatives: Any other straight-shaft mountaineering ice axe, they're all pretty similar with cost correlating inversely with weight.
Bear Canister: BearVault BV500
Best compromise in volume/weight ratio and cost. Opening tip: press the little ridged patches with a narrow, rigid object to save your fingernails, like a flat-head screwdriver on a multitool.
Alternatives: Bearikade, very expensive but you can easily rent it.
Stove: Jetboil
These are really well-designed stoves that I have never used. But I have met so many backpackers and mountaineers over the years who swear by them. For the PCT, one of the models with the wider pot (much easier to cook in and eat out of) would work well. Saw various models on the trail.
Alternatives: Various, most canister stoves work well Saw everything from a $10 Chinese stove from Amazon to ultralight titanium models on the trail.
Stove: Jetboil
These are really well-designed stoves that I have never used. But I have met so many backpackers and mountaineers over the years who swear by them. For the PCT, one of the models with the wider pot (much easier to cook in and eat out of) would work well. Saw various models on the trail.
Alternatives: Various, most canister stoves work well Saw everything from a $10 Chinese stove from Amazon to ultralight titanium models on the trail.
On Rain Gear
Rain gear was all over the map. Some didn't bring any, some relied on umbrellas, some went for trash compactor bags. Ultralight 2-2.5 layer breathable fabrics like Patagonia H2No and Gore-tex Paclite work ok, but will soak through in sustained rain or when pushing through extended wet brush. Pockets on such garments, even with sealed zippers, should not be considered waterproof (another hiker and I both found this out the hard way with our damaged phones). A rain skirt and poncho made out of trash compactor bags might work better because they're impermeable. Light rain clothes are useful as wind/bug protection. I mainly used my rain pants as a cold weather layer. Doing Mt. Whitney in the morning would have been impossible without them.
On Cuben Shelters
A lot of raves about these. They're light and pack up super small. Some mentioned pinholes, but not large enough to let in water. They can also be patched easily with duct tape (the adhesive won't permeate the fabric, unlike with nylon). Tricky siting, takes a large area to stake out fully due to the lack of poles, hikers mentioned getting "creative" with the pitching. Probably ideal if you think you will cowboy camp a lot and need an emergency shelter.
On Cowboy Camping
I did this a lot less than I expected. Some hikers reported cowboying anywhere from 60-90% of the time on the PCT. I probably did it 10%. I like having a bug/rodent barrier (though ants, rodents occasionally chew through the fabric), and setting up and taking down my shelter was pretty quick. There's some psychological comfort in having four walls that helped me sleep better. Still, the mornings waking up to an uninterrupted view were really nice.