There's also Divine Divinity, it's often forgotten, and I thought it was (and still is) great, I bought it on GoG.com very recently (two months ago) based on the recommendations I received when I made a similar thread on another discussion forum, I had doubts because... well, the game is old, not just about the graphics but the game-play mechanics, then I bought it, and I certainly do not regret it, I've yet to complete it however, I play it occasionally but it's a nice time burner in the veins of the action-RPG genre (although Divine Divinity is a bit more complex than just being an action-RPG).
At the moment though, and from "recent" releases, the only real Diablo clone we have is Torchlight, in my humble opinion. The others are similar of course, but they all tried to reinvent a few things left and right, often failing at it, sometimes doing it decently. If you want good graphics there's only one choice in my book and it's Sacred 2, but be aware that it has a price, and that is stability, it is known to be filled with various small bugs and stability issues, some people claim to have never experienced a single problem with it, others claim the game is barely playable, it's very volatile apparently, in my case I had to remove the grass entirely, play under Windows XP compatibility mode and add a command line to the game's launcher to make sure that the game wouldn't crash or freeze after some time, and so far (crossing my fingers) I haven't had a problem with it, but truly and I repeat myself, Sacred 2's biggest advantage is certainly the graphics, especially the shadows and lightning effects (mostly noticeable at night) and the water, it's just pure bliss for the eyes.
Lastly but not least I would recommend Titan Quest: Immortal Throne, with the community-made unofficial patch which in my opinion is essential. Additionally, TQ's graphics are quite good, not as good as Sacred 2's, but still good by today's standards, I just don't like the animations much, but otherwise it's a fine game, it could have been better in my opinion but it's alright, my only real complaint about it is the amount of time it took for it to become interesting, it was really painful to go through Act I without anything interesting going on and having to complete all those generic quests from NPCs we don't give a damn about, but I guess that it's also a principle that applies to Torchlight and many other similar games around, the problem is that it seemed to be more prevalent in TQ for some reason, it's just very long before it starts to get interesting, and the enemies' variety is lacking a lot during that time. And the same thing goes with the items, the drop rates for interesting items (at least on the Normal difficulty) are just pathetic, but I guess that it also depends on luck (or bad luck, in my case).
Anyhow, you've got multiple choices, there's more than what has been suggested so far but most of them may be too old for your tastes especially if you want decent or good graphics. If what you want really are graphics to start with then you don't have many choices, I would say Sacred 2, Titan Quest, Dungeon Siege II and Torchlight, in this order.