piggybacking on what brandon said.
i have 2 packs, the swift and the circuit. both great packs, but often wishing for something in the middle for many longer hikes. a swift with a circuit style delrin hoop (or i guess carbon tent poles acting as pack frame) would be ideal for me for most thrus. however, i'm thinking more remote than the AT. for the AT i think a frameless is fine. i carried an ION on the AT. for CDT (or similar with more food/water carry) I would want the light and durable swift with suspension, but not quite a circuit given my evolved kit.
that said, people thru with both frames and without. just figure out how much gear and consumables you'll need.
as far as your 'jack of all trades'--i'm always trying to simplify my gear towards that goal too: a circuit style pack is really versatile for large or small loads. carries both great and it compresses to a really small size, pretty much flat against the back. great for winter and mountaineering gear. and i think most frameless packs can be almost as versatile if you stick your tent poles inside as a frame. I like to climb peaks when hiking, so for 3 season, the swift is taken due to mobility. fwiw, i take frameless packs on desert hikes, sometimes carrying 9 liters (in 1.5L bottles: 3 on shoulder straps, 3 on hipbelt, 3 in waterbottle pockets). so really, you can thru with quite a range. a lot is preference.