Imma be different (and shocking) here in that I prefer the earlier games visually. :x Beware, you might think I'm crazy after reading this???
Okay, well, remove RBY, but Gold and Crystal definitely felt like a whole other world to me. I could visualise everything when playing through and there was such intrigue as in what was beyond that, even if it was just simple pixels. Like, Goldenrod... okay no, everywhere. I was young then, I had an active imagination. However, I still have an active imagination. Unova specifically I keep visualising wherever I go (cue calling me crazy), as in, everything reminds me of how Unova in my mind looks, and I just... whatever I look at I can see the "real Unova" in another dimension but yet it's actually here, even if it's something simple. However this isn't always automatic and does involve some effort, whereas with early Johto, I used to dream about it a lot and I think that sparked my imagination back then a lot, so if things remind me of Johto, they just do, rather than for reminding me of Unova where it takes a while. Unova doesn't have a sense of "what's next, what's beyond?" and feels closer to our world, more like a secondary dimension, while the original Johto games feel like a third dimension in that... they are just different. Like the daycare route - that little area with those people, the three that challenge you, when thinking back on that in my mind I can see a whole lot of things, of a distant world (which Unova can do and a lot of those visualisations kind of warp together sometimes). Um, let me describe. I think of like, mid-high, metallic stands, pixellated, but birds nearby, and a raft - not realistic, but of another world. That's what I get from Johto of that area, and I can definitely expand on that. I'm especially interested in Glitch City and the beta screenshots of Johto because it does get me thinking about the actual places that they would be if they were in a third dimension, as opposed to Unova which has the forest-y feel which is kind of more realistic to me. I mean as I said I don't specifically go out to think that, it just happens, which I think is pretty awesome, since anywhere I can kinda warp into Johto or Unova, or it does it for me.
HOWEVER I AM STRAYING FROM THE POINT. I think the thing that makes them stand out personally is that they both had a major role in my life to be able to remember them. Johto was when I really got into Pokemon, and therefore anything relating to that or memories related to that are now therefore the graphics I prefer. Unova on the other hand was originally significant to me too and therefore stood out in my mind, but even before that, a few months before the original B/W games were released, I randomly started getting these visualisations of this city, and then Unova comes along and it kinda matches that, and other places I thought of before the games match up with my visualisations, and even dreams too... I mean they aren't entirely the same but I can just get the feeling that they are related. Due to both (well G/C and B/W) having an impact on me I therefore have a preference to both of those, however while I get these visualisation things of B/W, it's not during playing B/W, and rather outside of playing B/W, while for G/C it's definitely during playing them, which makes me have a preference towards those graphics. Also that tied in with childhood memories gives me a preference to that. I like the unknown, rather than the games telling me to visualise like in HG/SS which didn't really appeal to me because it didn't capture the original thing and I don't visualise anything about HG/SS. No other games do this for me, so ya.
I'm not strange I'm creative? idk. :( I kinda wanted to get my thoughts out there anyway lool. I hope that was all relevant!!