I have nostalgia for both Gens II and III but I find Ruby and Sapphire to be the least favorite games though I still like them. I hate that you cannot transfer from RBYGSC. Emerald, FRLG, and the Gamecube games were good though. Gen II also got boring after a while.
Oops accidentally chose Gen 3 which appears to be losing this poll due to the sheer fact many people longed and actually anticipated remakes. IMO! But honestly I liked every Gen but looking back I can definitely choose one that seemed to be a chore the last time I went through it.
Opinion on bad things in each Gen.
Gen 1- You can't really dislike this Gen other than for it being severely outdated. Even its remakes are outdated. This Gen is what started it all. There is no denying, any Pokemon can attest, this game did something right.
Gen 2- Kanto! Awesome idea, terrible execution. You travel to Kanto which once thrived as a region 3 years in the past but now has become desolate, run-down and completely unappealing. It felt sad walking through the remnants of a once great locale. The designers rushed this. Though it is the largest area in a game post elite four to explore.
Gen 3- Bad things... Team Aqua and Magma weren't too bad but were sub-par but other than that.................. TOO MUCH WATER! My biggest gripe. Because of this game I have begun to dread EVERY water route I've come to in preceding Gens. True stuff. I did enjoy the music, Pokemon and the scenery introduced. Never played Emerald so don't really acknowledge Wallace as a champion.
Gen 4- Hmmm I'm not one to complain about Pokemon, I welcome any and most but for some reason the majority as a whole didn't quite appeal to me. Though this Gen had some of the coolest. The rival SUCKED and I found Team Galactic tedious and generic. The gym leaders is what really got me though. Roark, Volkner and Candice were cool. The others okay but the ghost gym leader, Wake and Maylene. Ugh. Their gyms were like a marathon cycle with no rest or time to sight-see or get side-tracked. It was repetitive going straight for the gym. I think on my last playthrough I knocked their gyms out in like 2 hours and I was taking my time. This is Platinum. Anyway, end rant. This is my least favorite Gen but I definitely enjoyed it my first playthrough.
Gen 5- Castelia City, stupid gimmick. Did not really care for the music this gen, especially the Castelia and Nimbasa themes. Annoying! Seismitoad was poorly designed. Liked near all of the Pokemon but didn't like how some evolved at really high levels. Did I mention Castelia City?
Gen 5 might just very well be my favorite though I've played through it at least 4 times and can't bring myself to do it again in prep for Gen 6. I've played through the sequel only once but I guess that was good enough for me because I can't do it again. Plasma is getting annoying and the music isn't all tht great with very few exceptions.
Gen 4 is the worst. Pretty boring IMO. (Gen 5 is the best)
I'm surprised by the hate toward gen 2. I remember when HG/SS where announced, everyone were so hyped because it was one of the favourite gen and now it is almost treated as garbage. Well, I don't really like Gen 2 but still.