baldur's gate 2 has more to do in it. There is a lot more interesting character development (at least story-wise). It's also a lot harder, on the whole, if that interests you.
Diablo 2 is a bit more shallow then BG2, but by the same token, it's a lot more refined. The gameplay has a lot more action in it, and the act of building a character and getting him adequate equipment can eat lots and lots of hours. The game also looks much better then BG2, as BG2 was running on the engine that had been powering its predecessor, without almost any graphical updates to it.
If you like a game with a lot to do in it, I'd suggest Morrowind. But if I had to choose between those, I'd suggest BG2. I preferred Diablo 2, as I found building a character to be a lot more interesting from a gameplay perspective in D2 then it was in BG2..
but it's largely a matter of taste.
Artemis923 said:
I'll take 2nd AD&D over the cesspool that is 4th Ed. any day.
Just out of curiosity, what is your beef with 4th edition? I thought the same sort of thing when it was first announced, but once I started using it, I found it to be a lot easier on the players, and the DM, and making for a much more interesting game.. again, it's a matter of taste, but I'm wondering how much you've actually played with it