As one of the few who loves X/Y, seeing some appreciation for them in this thread makes me very happy. It annoys me how the fandom generally seems to focus on the negatives of X/Y while ignoring their positives (compare this to S/M which often seems to be getting the polar opposite treatment). I remember that in the past, X/Y were very positively received when they were first released, but sadly, it seems like they are the least liked games in the fandom nowadays.
Personally, I have always been a big fan of them. I don't care much for story or difficulty in Pokémon, but I do appreciate many of the other things X/Y have to offer. Epic training spots, an amazing multiplayer gadget, a large regional dex, great Pokémon distribution/variation... and a National Dex. Those are also things that S/M were desperately missing... I guess it is obvious which of the two first pairs on the 3DS I like better.
I agree about X/Y being a step down from B2/W2, but they are still excellent and I personally consider X/Y to be the closest the the series has gotten to a true successor to Gen 5. I think X/Y built upon many great things that started in Gen 5.
I have posted everything I like about X/Y
in the past so I won't repeat it all once more. Overall, I am a big fan of X/Y. Even if it has been almost 9 years since their release, and even if I have played OR/AS, S/M, US/UM, Sword and L:A since then, X/Y are still my favorite main series games in 3D.
I am also a fan of OR/AS. As one of the few people who didn't like HG/SS, I really like how OR/AS showed that it was possible to make another good remake after FR/LG. I was initially not very hyped for OR/AS and I didn't even get them on their release date, but I eventually got them and the more I played them, the more I liked them. Nowadays, they are my favorite Pokémon remakes.
On the whole, Gen 6 is my second favorite. When it comes to the things I consider important in Pokémon, it does almost everything right and very little wrong. X/Y are my third favorite games in the series and OR/AS my fourth favorites.
I am also a bit surprised at how badly BD/SP seem to be received within the fandom. People generally seemed very positive to them during the pre-release period, but it seems to have changed. I have not played these games so I can't really speak for them... but I guess the fact that I haven't played them speaks for itself.
On to other things. I saw some posts in the annoyances thread which reminded me of other things I really like. First of all, I am a huge fan of infinite TMs. When I play Pokémon, I usually focus on the post-game way more than the main game. So in Gen 5-7, I really appreciated how I only had to obtain a TM once as opposed to multiple times if I wanted to teach a move to several Pokémon. In comparison, it was a bit dull when I played R/S/E or D/P/P and wanted to teach a move like Thunderbolt/Flamethrower/Ice Beam to several different Pokémon. In order to do that, I had to grind up the money to buy a lot of coins from the Game Corner so I could buy several TMs. But in Gen 5-7, I no longer had to do that. I can understand that they wanted to "balance" things better with the TR/TM system in S/S, but I do not approve of it as it makes the games less enjoyable when it comes to the way I play them. I also find it ironic how BD/SP does not have infinite TMs as that is one of the things I am really missing in Gen 4.
Another thing I like is how Move Tutors work in the newer generations. In Gen 3, they could only be used once in FR/LG, the same went for several of the MT moves in Emerald. While there are some positives about this as green_typhlosion talked about
here, the fact that they are one-time really takes away from it IMO. Another annoyance from the past is how MTs required BP while also being pretty expensive, this happened in Emerald and HG/SS.
But other games have handled them much better. In Platinum and B2/W2, they cost Shards instead of BP. Shards are thankfully very easy to farm in those games thanks to the Underground and the Funfest Mission "Find Shards!". In OR/AS and US/UM, they cost BP once again. But they are now much cheaper than in Emerald and HG/SS, and BP are much easier to farm here thanks to how the Maison/Tree gives you BP after every battle. So I really like how obtaining MT moves have gotten better over the generations.
Lastly, one random minor thing I just remembered. In US/UM, Nanu calls Mina a filly during her trial. I don't know why he decided to call her that but I find it incredibly funny.