Geez, that was a tough one! I thought about Tomorrowland, but that was back in the late 80's/early 90's when it was good...now it is kind of lame. Anyways, Frontierland was a thought, too. The combo of Big Thunder and Splash Mtn is a good one and then I always liked the tranquility of Tom Sawyers Island and the sound of the steamboat whistles. But, in the end, I picked Adventureland. It used to be better when the Adventureland Veranda was still open and before they put the eyesore called Aladdin in there. But, overall it's the most interesting area for me. The POTC, Jungle Cruise, Tiki Room and Swiss Treehouse are a nice hodgepodge of attractions.
BTW, here's my ranking of the themed lands
1 - Adventureland (POTC, Jungle Cruise, Treehouse...tribal drums, lush landscaping)
2 - Frontierland (Big Thunder and Splash! Tom Sawyers Isalnd. The Rivers of America)
3 - Tomorrowland (This used to be my fave when we still had the old COP, Dreamflight and AE)
4 - Liberty Square (HM, the howling wolf at night, HOP)
5 - Main Street USA (The view of the castle is awesome. It always is cool to walk down, too)
6 - Fantasyland (Used to be better with the Skyway & 20,000 Leagues. Too crowded and full of kids, though)
7 - Mickey's Toontown Fair (Just an afterthought. Way too small and way too kiddy for me. Disneyland's is better)