I have done several long distance hikes, including the Appalachian Trail, a solo Traverse of Alaska, the Pacific Crest Trail, the Continental Divide Trail and the The Desert Trail. Following is what I might carry were I to thru-hike the Appalachian Trail again and was just buying gear. Most of this gear is “top-of-the-line.” If you are on a budget, you can sacrifice a little quality to save money.
It’s important to recognize there is no “perfect gear.” Gear selection involves compromise. It’s largely a balance between comfort while walking (a light and comfortable pack) and comfort while in camp (warm bag, good shelter, enough warm clothing and food, etc.) and expense. There are luxuries that would be nice to have but whose weight is not justified in climbing thousands of feet and walking many miles every day. Also, gear beloved by one person may be disliked by another. Combine your own experience with the advice of veteran backpackers to make your decisions. Don’t over-think your gear. Success is mostly mental.
You’ll want to be warm enough, and dry enough, and comfortable enough, and part of being comfortable is having a reasonably light pack. A reasonably light pack will make your hiking more fun and it will be easier on your body, specifically knees and ankles. I would recommend keeping your base pack weight (your pack and everything in it except food, water and fuel) under 20 lbs. 15 lbs or less is an even better target. The “Big 3” is a good place to start with weight reduction: shelter, pack, sleeping bag. Nowadays my “Big 3” weigh less than 5 lbs.
If you get cold easily or are starting in late winter, you might want to add a down jacket to the list or otherwise modify it to make sure you stay warm enough.
Now, my packing list. These are examples of what I consider to be good choices.
Pack: A very popular A.T. pack is the Osprey Exos. If you choose the best size and fit for you it might be a hard pack to beat. For ULA pack fans, the Circuit or CATALYST will be a better choice for most. It’s a very popular pack for thru-hikers.
Shelter: Six Moon Designs Lunar Solo (23 oz.) I used one on part of the CDT and in Washington on the PCT and on many other trips. It sheds rain well, and has a built in floor and bug netting. Also outstanding are Tarptents. Both these manufacturers make very good shelters. You might also research backpacking hammocks. There are constructed shelters on the trail, but there will be times when they will be full or noisy or you will end up between them. Carry your own shelter.
Sleeping Bag: Enlightened Equipment Revelation Can be cinched up like a bag or opened up like a quilt. Warm for the weight. Personally, I’d go with the 20 degree version with DownTek. 20 oz. I line the stuff sack of my sleeping bag with a Mylar turkey roasting bag. I also line my pack with a trash compacter bag.
Sleeping Pad: Thermarest Prolite Plus , Small (15 oz.) A good night’s sleep without tossing and turning is vital. This mattress is self-inflating and 1.5 inches thick. Younger hikers might need less padding and prefer a closed-cell foam pad. If so, it’s really hard to beat the RidgeRest SOLite at .625 inches thick. A small weighs 9 oz and is 48″ long. A regular is 14 oz. and is 72″ long. 48″ is long enough for most people when they put their pack or other items underneath their feet. Some might want to buy a regular length and cut a piece off one end to use for a “sit pad” for breaks along the trail, and at night to prop up their feet.