I voted new, especially the current HD gen, I think in 10 years people will look back and see this a golden era of RPGs.
Single player story based rpgs: The Witcher, Mass Effect, Dragon Age and NWN2:MotB are better games than anything I've played in the past, including Pools of Radiance, Baldur's Gate II, Planescape.
Single player story based rpgs (non hd): From new games but non-hd-gen, Kotor, Kotor II and Vampire:Bloodlines were pretty awesome. Only new games I couldn't get into are NWN 1 and Jade Empire.
hack & slash: Torchlight, Diablo II, Oblivion and Morrowind (I also liked Demonstone) pretty much blow anything old, can't wait for Diablo III. PS3 owners I envy you, Demon's Soul looks awesome
MMOs: no question, nothing can beat WoW and the very old mmos were terribad in comparison to what we have now.
JRPGs: can't really compare, I stopped playing these after I stopped playing on my SNES, I'll give Final Fantasy III remake on the DS a thumbs up tho.
I'l give a couple of plusses to old games tho,
- BG II:SoA has a better villain & story than DA:O but I usually compare DA:O to BG I, both are pretty generic games introducing the player to a setting. My guess is that DA II will blow BG II's villains & story. On total DA:O > BG II.
- Planescape was more original than MotB, but it's pretty close. Overall as a game MotB is still much better though, PS:T is way too old to get into these days.
- Some combat mechanics did make the games more interesting, e.g. needing acid to kill trolls, or changing the memorized spells for specific fights.
- Older games didn't have payable DLC, *all* content was on the CD.
- Older games had more content. Today games as big as BG II+ToB are hard to make because the effort it takes to make these voiceovers & detailed graphics doesn't allow it.
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* I'm not commenting on some recent rpgs claiming to be old school, never tried them, never will, their graphics seem worse than some of really old school RPGs (they beat only pools of radiance graphics-wise).
* can't comment on the Fallout transition, I hadn't finished FO2 back then and I haven't played FO3 because I'm not terribly fond of the scaling in Oblivion and a friend told me FO3 scales as well, maybe I'll give FO:New Vegas a shot is battles don't scale.
Overall New > Old but it's not like *all* recent games are gems and all old ones are rubbish, I'll always keep my Baldur's Gate & PS:T CDs.