I don't know. All the towns from Gen I and II are memorable to me. A lot of the ones in the later games try to be different or have some gimmick and they all just blend together for me. The only one that stands out for me is that tree city in Gen III. I think too much of the scenario now takes place just outside of a city in warehouses rather in a city building.
My favourite generations are 4 and 5. Maybe it's just that I was so disillusioned by all of gen 3 (I hated RSE and really didn't like FRLG for some reason) that any departure from it was great to me, but they just tossed me so far back into the Pokémon fandom that I can't help but love them. My absolute favourite Pokémon is from gen 4 (no points for guessing what it is). Recently, I've been doing sort of an art meme where everyday I draw my favourite Pokémon from each type and the gen that has the most favourites? Gen 5. I know the formula is old and pretty boring, and tbh I didn't enjoy the story in BW much at all (though part of that may be because I had no freaking clue what I was doing when I imported Black because I was too lazy to read the text). But the only reason I liked HGSS was because of the Cherrim following me around and I find it difficult to go back and play gen 1 or its remakes. I just got so bored of them. I didn't like Emerald when I finally played through it a few years ago and I just... I adore Sinnoh and even most of Unova. It makes me so sad when people come down hard on them simply for being too much of the same thing without giving them a chance. I can understand just not liking them but I can't stand the Pokémon purists who won't even bother because "all [they] need is 150 Pokémon" or something like that. My favourite Pokémon, in roughly this order, are: Cherrim, Pichu, Probopass, Vanillite, Chandelure, Nosepass, Cherubi, Bidoof, Drifloon, and Litwick. Only one of those is from an earlier gen. Only three of the Pokémon I even consider in my "top favourites" are from gens 1 and 2. And a bunch of them are the kinds of Pokémon people point out as being horrible when they try to explain why the newer designs suck, so I get kind of sensitive about the topic. xD;
I love Gen 2 and Gen 5. Johto is just awesome and stuff. It was the first Pokemon game I pretty much did myself. And Gen 5 is just so good and way better than Gen 4.
I liked Generation III the best. Hoenn was my favourite region, so yeah. FireRed and LeafGreen were pretty fun too, with the addition of the Sevi Islands.
The towns were smaller, but more recent Pokemon games don't utilize their larger towns well. It's just meant more NPCs to have inane chat with, and Pokemon games are so slavishly determined to be as all-ages as they can possibly be that a lot of NPC dialogue consists of thinly-veiled tutorial content that you should have already known if you read the manual. I don't want to be in town six or seven of a Pokemon game and have NPCs still saying things like "did you know that some Pokemon evolve when traded while holding an item?" or "Herbal medicines are great for healing, but Pokemon hate the taste!" when they could be being used to give their locales some flavor and character like most other RPGs do. When have Pokemon games EVER had developed characters? They've always had silent protagonists, Rivals are just different shades of megalomaniac, Gym Leaders consist of wacky clothing and a couple of throwaway lines before and after a fight. Also (and I know we'll never agree on this point because of how many times we've debated it before) Gen 1 Pokemon designs are the best. Most of them are organic, believable, and elegantly simplistic. Now we have Digimon and ice cream cones with faces.
Generation 3 is definitely my favorite. Generation 4 and 5 kinda tie together, because they've impacted me greatly as far as competitive battling is concerned and whatnot. n___n; Generation 3...I had a lot of fun with it, especially what with the Battle Frontier and all, it was definitely a whole bunch of fun. xD; But yeah, thats just me.
FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN FIRST GEN I dunno maybe first gen.