Updated graphics tend to be something important for me, as it helps with immersion. However since the generations get redone when the graphics improve drastically, I think it doesn't really matter what is classical or what is new. Sooner or later everything is new again, and one can relive the game as if one were playing it for the first time.
My favorites are still the classics. Especially Pokemon Gold for the Gameboy Color. The new games are fun but they just don't keep my interest as long as the other newer ones do. It's probably because I'm older now though.
I think I like newer games more than the classic ones, solely because I started out with Pokemon Diamond and I was spoiled by the many mechanics that game had.
I prefer the 2nd generation because the programmer's look like they've mastered the whole concept of the Pokemon universe with the 2nd generation games. Big maps, interactive characters, impressive storyline and all. Alhough it was the Blue and Red games that started it all so I have a sentimental bias towards it.
Classics for the nostalgia involved, the game has gotten a little away from the main point of the game I think so I'll stick to my old shit.
I love all of the games, but when it comes to replaying, it's the newer ones. I get a bit of a shock when I do throw an old one in, because it's so different!
I'm definitely a fan of the classic ones. The inclusion of so many more Pokemon inevitably leads to more bad eggs, and the original 150 Pokemon are still among the most interesting of the series.
I prefer the graphics of the older games. I like the new 3D stuff, but I don't think it has the same charm. It would be nice to go back to the old graphics, but while introducing new features etc.
I like the newer versions of the older games. Kanto and Johto are still my two favourite regions, but I have trouble revisiting them with the restrictions of the Gameboy. The GBA and DS versions are much, much better. I find the newer games less and less interesting because they do seem to lose sight of the core aim of the series, namely to build up a strong team and challenge an intimidating Pokemon League. That stuff is still there, but because of the tweaks to levelling they're so much easier to handle.
To me the classics were the best. They kind of lose the touch when the have remade the game for the umpteenth time with clones of a particular kind with no real work on the story. I mean there is always a set of bugs at the beginning, always a trash one like rattata, always a pidgey replacement... and so on. It gets old fast.
I like both equally, to be honest. Each generation of Pokemon, old or new, has there own unique charm, but if I had to choose, I would choose the later ones as they are usually more polished with less bugs and such that the earlier games had.
Right now, I've been playing the newer ones and I've been loving them. I haven't played since gold and silver, so they're all new to me lol
I'm playing newer fire red over since I hadn't played it yet. I have to say I really appreciate all the little touches they added. Even when I played the old pokemon blue over, I was shocked at how convenient little things like just the popup message to cut a tree, makes the game better. Never know that's its better until you try it I guess.
Personally I prefer the classic ones, but that's probably because I grow up with that games an with that pokemons. The new games are pretty cool, don't take me wrong, but the classics will always be my favorites.
I find the new games way too easy to beat. I miss the challenge of the classic titles. Specially Red / Blue in the original game boy. TM's not reusable and ridiculously small room for items for example, were limitations inherent to the platform.
Classic will always trump the newer ones, for the sole reason that it has nostalgia factoring in. Newer games have better balance, better graphics, longer gameplay, but all of us would prefer Pokemon Red, Blue, or Yellow over these because they remind us of our childhood, and they can never be beaten. The original 151 Pokemon will always be better than everyone else, even though some of the concepts involve a mud Pokemon, a Pokeball Pokemon, and even a magnet Pokemon. Nothing beats childhood nostalgia.
I love the classics, they will always have a place in my heart. However, I feel that the newer ones have a bit more to offer and have more interesting stories within them.