Well, I dunno. That's a pretty tall order for a bootholding up from snow through hot weather, plus just a damned lot of miles. I lay no claim to hiking the AT, but the drill is: packs of 30 to 40 pounds, intermittently rocky/wet trails, 10 to 20 miles a daypretty demanding.
If I were to go to my gear stash in the garage, I'd probably grab my Scarpa Kailash's ($185). These are just fantastic all-around boots. Light, waterproof, comfortable, good support and traction. Id have some question about their durability over three months of hard work, but I think they would be okay.
To really pack the freight, maybe Asolo's TPS 520 GV ($250). Heavier than the Scarpas, but full-grain leather one-piece uppers will easily make the trip from start to finish. And they're still very comfortable, easy-to-walk in boots. Waterproof, too.
Sorta in-between: Kayland Zephyrs ($190. Sort of a new-age boot with a plastic "exoskeleton" for support, plus all the usual goodies like Vibram sole, eco-friendly Cocona liners, etc. Nice boots.
Be sure to take the time to get the right fit. That, by far, is the most important thing.