Favorite Generation:
Probably 4 as of now. It's impossible to deny that each gen has added tons of new features that have made the gameplay a lot more fun and engaging. Only thing holding me back from saying 5 is that it took away so much. (game corner, cycling road, battle frontier, etc) But with the 3rd version coming out, I'm sure Gen 5 will become my favorite, especially with the imminent reintroduction of the Frontier.
Favorite Region:
1. Johto. Not even just for nostalgia, I thought it was the most interesting and balanced.
2. Kanto. The classic. There was a lot to do, and I liked the immense amount of backtracking required.
3. Sinnoh.
4. Unova. I hated the awkward shape that it makes around the Entralink. It just seems too unnatural. And as much as I hate to say it, too many bridges...
5. Hoenn. This reigon was just so awkward. It never really felt like a Pokemon game to me. :/