I'd probably have to say it's Generation 6, despite some problems it has. Generation 6 simply had so many great features all coming together to make a very enjoyable experience:
- Breeding competitively viable teams and shinies had never been easier, thanks to the Destiny Knot's ability to pass down IVs from the parents and the Everstone guaranteeing the nature of the parent holding it would be passed on to the offspring.
- EV Training, similarly, was made so much faster and simpler with the addition of the Super Training feature of the Player Search System. I love Super Training and was greatly disappointed by its omission from Generations 7 and 8.
- Since I mentioned it, the Player Search System. That was a fantastic system overall. While I enjoy certain aspects of Generation 7's Festival Plaza, particularly the Dye Houses, I felt and still maintain that its features should have just been folded into stores and NPCs in the world and the Player Search System should have returned.
- Mega Evolution is a fun gimmick, and it's a shame that in Game Freak's desire to make each generation unique they abandoned it, because there were so many other Mega Evolutions that I would have liked to have seen. Cacturne and Flygon especially feel like missed opportunities, and I would have liked other ones for Pokémon who always got overshadowed by others, like Hypno being overshadowed by Alakazam, or some that don't get that much attention like Arbok, to get some limelight. I also really, really wanted a Primal Reversion for Regigigas, who is one of my favorite designs in the series but who is absolutely dreadful to use. A lot of unrealized potential squandered.
- The introduction of Trainer Customization was a huge deal. It's limited compared to Sun/Moon/Ultra Sun/Ultra Moon and Sword/Shield, but I like the unique clothing options present. They also allowed your trainer to be a redhead, something that's missing in all of the games since, which was cool. The only downsides were that you couldn't remove the hat in X & Y and couldn't customize May or Brendan in ORAS.
- I missed the initial Generation III after quitting the series for a few years due to a combination of peer pressure and being at the age where you sometimes feel like you're "too old" for things you enjoyed as a kid. As such, I had an absolute blast with Omega Ruby and Alpha Sapphire as my proper introductions to Hoenn. I've since acquired and played through some of the Generation III games, but even still, with all of the quality of life advancements made since then, I greatly prefer ORAS.
- Kalos, while too easy in terms of difficulty, was enjoyable to me in terms of the region's design and the Pokémon introduced. Some favorites like Pumpkaboo and Gourgeist, Trevenant, Malamar, and Aegislash were introduced here. I also enjoyed certain aspects of the story, particularly Lysandre (the rest of Team Flare was a massive disappointment though) and the post-game Looker mission.
- Hoenn was a collector's dream with the past Legendaries being acquirable with the Soaring feature. It also had more difficulty than X & Y and the Elite Four and random trainers actually increased their levels upon battling them again later. What it lacked (no Trainer Customization, as mentioned earlier) it made up for in other ways.
- I was also fond of the nickname gimmick in X & Y, as silly as it is and as bad as the default ones the games suggested were. I would have liked if they kept allowing your characters to have nicknames certain characters would call you, it added something to the experience.
To answer the poll, I'd say I'd definitely take Omega Ruby & Alpha Sapphire X & Y, so I voted for Other Game due to the Remakes section.
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After that, I'd probably rank them as follows:
Generation 7: I don't really like the lack of gyms, but the Island Challenge was an okay change of pace for the generation. Cool new Pokémon like Rowlet, Litten, Golisopod, Midnight Form Lycanroc and more, as well as neat Alolan Forms like Alolan Marowak, Alolan Muk and Alolan Raichu. I adore the Dye Houses, and Trainer Customization overall was pretty good. Sun & Moon had the better story, while Ultra Sun & Ultra Moon had the better gameplay. If Ultra Sun & Ultra Moon hadn't come out, Generation 7 would probably be ranked lower because original Sun & Moon underwhelmed me, but USUM added enough unique things to boost it up to second place.
Generation 5: Last games with the old sprites, enjoyable region with cool Pokémon. While other people didn't and don't like that you only had Unova Pokémon to pick from unless you transferred in the post-game or traded with someone who did, I personally loved that. Also, the Pokémon World Tournament was pretty cool.
Generation 4: Pokémon HeartGold and SoulSilver drag Generation 4 to this placement, and the only reason they're not higher is because of the quality of life advancements made in the games afterward. HeartGold and SoulSilver are just amazing experiences and I wish Pokémon games could have kept some of their aspects. Diamond/Pearl/Platinum are fine in their own way, Sinnoh is decent, but the experience of playing the games kind of underwhelms me. I'm open to seeing if remakes on the Switch make them more appaling to me though.
Generation 8: I enjoy certain aspects, but I'm not really in love. Dynamax and Gigantimax don't really hold appeal for me, and raids feel half-baked for what could have been a cool concept. The trainer customization has nice offerings and the Gym and League battles being in sports stadiums is a fun concept. It's kind of annoying that you can't decide what uniform you use in the gym battles though, having to stick with that basic white rookie one even if you're the champion.
Generation 2: Crystal was my absolute favorite Pokémon game for years until HeartGold and SoulSilver came out, when they took basically everything cool about Crystal and made it even more awesome. Well, with the exception of them replacing Kris with Lyra. Kris was way cooler than Lyra and, while I recognize the Kris name wouldn't really fit anymore, it was a bummer to lose her. Generation 2 was fantastic, introducing a bunch of cool new Pokémon and allowing us to explore not only Johto but also revisit Kanto and earn their badges too. They're like the gold standard of what a new region should be, and it's a shame that Game Freak doesn't see it that way. It's only ranked this low because of the advancements made to the series since, which makes the games listed above it more enjoyable to play these days.
Generation 3: While I missed this generation when it was current, I revisited it later. It's neat, both Ruby/Sapphire/Emerald and Fire Red/Leaf Green, but the Physical/Special split wouldn't happen until Generation 4, which makes going back to these games kind of awkward now. A lot of good Pokémon were introduced in Hoenn, it's probably one of the strongest rosters they've had in a region. They're good for what they are, but yeah, they just feel a bit too outdated to me now.
Generation 1: I started with Generation 1 back when Pokémon first hit the United States in 1998. Those days hold a special place for me, but that doesn't save them from being at the bottom of the heap nowadays. Far too many improvements have been made to the series since. Generation 1 is simply archaic, and now they have the added burden of having been revisited too many times and feeling overexposed.