It depends on what you're looking for. D2 had better monster variety and more gameplay variety than D1, but has more abstract levels than D2. I'd like to see D1's levels recreated with D2's monster/weapon variety in mind.
Overall, I don't think Doom 2 is actually much more abstract than Doom 1. I suspect the real difference is that all of Romero's levels were clumped together in the shareware episode of Doom 1, which is what everyone remembers. Sandy Petersen (who does the really abstract weird stuff) did episodes 2 and 3, but his Doom 2 levels were strewn throughout the game, even in the Earth-like sections that you'd expect to be more realistic.