I like some from each gen and are meh to some from each gen, I don't really have a favourite.
I like Gen 1's roster a lot overall, though some feel a bit mundane. I am kinda- USED to them though, because they've been there from the start. Still love them though.
Gen 2's has some designs I really like, and some mediocre ones, as well as a smaller amount than other gens. And most of the cool designs don't evolve. I love the different feel these designs have though.
Gen 3 hits the jackpot, so many good designs. Also the increase in graphics helped.
Gen 4's selection is meh, there's really not much here that's great. The new evoloutions more often that not were ugly, except a few. And the original lines aren't amazin mostly.
Gen 5 has a lot of Pokémon I like, and I like the wackiness and parallels to gen 1 Pokémon (and I love Vanniluxe) but also the average quota of meh pokemon.
So... yeah. I don't really champion any of them, but in terms of number of good designs gen 3 should win. However I still don't feel it was the best IMO. --- "France is a place for beauty....and beauty makes people want to sex you..." Nightinangle, on the topic of France Official Rayquaza of X and Y boards
Gen 1 was the first. It might be because of nostalgia, but many designs were great, and it all started with them...
Gen 5 had many very awesome designs. It's definitely number 2 in my opinion. Archeops, Carracosta, Cofagrigus, Chandelure, Kyurem (normal Kyurem), etc. Actually, the more I think about it, the more awesome designs I can think of. It's kinda on par with Gen 1, but nostalgia wins.
Gen 4 had many cool designs. I especially like the "ancient" theme it has. Rampardos is my third favorite Pokemon, and Torterra, Bastiodon, Mamoswine, Yanmega... they are awesome. Other than that I can't think of too many good ones though...
Gen 3 had some awesome Pokemon, but most of them were rehashes and boring. Even many of the original ones weren't that great. It does have my favorite Pokemon though. The legends in this gen are really great. And some Pokemon inbetween the normal ones, even though I can't think of one that is one of my faves... actually, let me check *checks*. Um... okay. It definitely lacks Pokemon with great designs. Although Metagross, Tropius, Sharpedo, Wailord and Medicham are nice.
Gen 2 was still good, but it had so few Pokemon, and so many boring ones. It still had great and awesome ones though. there was just too much junk inbetween though, which took up most of the spots. (so many pre evos... so many bad and weak or annoying Pokemon... Unown, Wobbuffet) --- I'm a the Luigi master! www.freewebs.com/luigi_player/
Gen 3 introduced a lot of Pokemon I like, so that's obvious. Gen 5 also introduced a lot of Pokemon I like, but not quite as many as Gen 3. Gen 1 introduced a good amount of Pokemon I like, but it's also kinda weighed down by a lot that I don't particularly like. Gens 2 and 4 are in the weakest position because they're smaller than the other 3 by a not-inconsiderable amount, and while they do have Pokemon I like, the ones I like don't stand out as much, and there are also quite a lot I just don't like (Politoed and the Chimchar line come to mind immediately). --- Official Bride and Wife of Noire (of the Fire Emblem Awakening message board)