Generation 6 is almost here, and I still haven't decided on what my clear favorite generation is. I think the reason is purely because I have two separate rankings for the generations: one based on the Pokemon designs themselves and how much I like that generation's Pokemon on a visual standpoint, and one based around the gameplay mechanics like moves, abilities, new features, etc. Because I do have these two different ranking systems, I can't agree on a ranking system that combines both into a general ranking of the generations. I don't know. It may just be me.
As I think about it more, I'm trying to think about everything I liked from each generation. But I must say, Generation 1 probably isn't my favorite for various reasons like the screwed-up type matchups, the Special stat, and a few of the Pokemon designs, not to mention the countless glitches and bugs the games had. Yes, I know, the games are nostalgic and whatnot, and don't get me wrong; it's not like I hate the games completely. Heck, without Gen. 1, we wouldn't be here today. And yes, I have played the Gen. 1 games, so don't go shaking your canes at me and telling me to get off your lawn. Bottom line: I like generations 2-5 (or maybe 6) more, and those generations are more likely to be my personal favorite. *awaits hate comments*