Here are some of the most essential items for my setup (tested for ~2000 miles in various conditions, like the PCT/AT):
- HMG Windrider 3400 backpack (“just works” better than any other UL pack I have used)
- ZPacks 20F sleeping bag (hoodless is great!)
- Patagonia Houdini wind jacket (extremely versatile layer)
- Patagonia sun hoody (essential for skin protection, in my opinion)
- Uniqlo Heattech extra warm leggings (the greatest clothing item of all time) + Uniqlo down hoody jacket
- Fleece pullover hoody (almost any will do—comfort/extra warm item).
- Thermarest Neoair
- Gossamer Gear 1/8” EVA foam sleeping pad for protecting the Neoair and a zillion other uses (e.g. yoga/picnic/door mat, makeshift rain skirt)
- Tyvek groundsheet (cheap, indestructible, waterproof, becomes buttery soft over time)
- Carbon fiber trekking poles (the ones from Costco are cheap/good)
- AquaMira water treatment drops (the Sawyer squeeze filters deliver fresh filtered water, but they break/leak constantly)
- 2x 1L Smartwater bottles + a 2L Platypus bag
- MLD Patrol tarp with an inner tent or bivy (like this: http://www.nwhikers.net/forums/viewtopic.php?p=522791). That’s about 16.0 oz (incl. good stakes) for a versatile and storm-worthy(ish) double wall setup.
Also, my Patagonia sun hoodie is my favorite clothing item I own. I wore it for a week in the Mojave earlier this spring. I was cool and comfortable the entire week and didn't even get a tan on my arms, let alone a burn.
As a rule of thumb: It is easy to buy a backpack that is too big. It is nearly impossible to buy one that is too small. The experience of a traveler is in an anti-proportional relationship with the size of his or her backpack.
This being said, the best back pack I ever had was from Burton. I and I am still heart-broken that it got stolen. It is not produced anymore.
There was a EU based, tiny equipment manufacturer that actually produced backpacks for very tall people. I had some contacts in travel related business that could have brought it back on track. I asked if the owner is willing to let me buy into the business (I was interested in other niche products in his business) but he preferred to close it down.