odd man out I enjoyed Sacred 2...
Diablo 3 Reaper is about ad close as it gets

I do prefer the atmosphere of Diablo 1, but Diablo 2 has the better gameplay.

And a more variety of classes.

Diablo 1 had the generic Warrior/Fighter, Mage/Wizard, Rogue/Archer.

Try Diablo 1 - Beelzebub, a properly enhanced HD Mod for Diablo 1:

http://mod.diablo1.eu.org/

My 2 cents (coming from a huge diablo 1 and 2 fan)

Path of Exile probably takes the cake as the closest thing to a diablo sequel (imo closer than diablo 3)

Sacred 1 and 2 deserve a shout out for being their own unique and quirky world while keeping some of the diablo like elements, I enjoyed both games.

Same goes for Divnity series, definitely worth checking those, but don't feel exactly like a diablo clone.

Titan Quest is a great game and maintains a solid diablo feel, but the lack of gore always bugged me, haha.

NOX doesn't really have a diablo feel to it, but it is a solid ARPG and definitely worth a play through or 3 (each character has their own story/game walkthrough if I remember correctly)

Dungeon Siege 1 and 2 are worth a look. Like others have said, DS1's gameplay is pretty simplified, but I still enjoyed it when it came out, and DS2 was much improved and feels like a legit diablo clone.

Dark Stone was one of the original diablo clones, worth a look.

Does anyone have an opinion one way or the other about Soulbringer?

Titan Quest on GOG, that would be great.

Because there ain't mention of it yet: ShadowFlare. Very underrated and well-praised Diablo-like from the turn of the millennium.

For games that play like Diablo, Sacred 1 and 2, and Divine Divinity and Beyond Divinity. Both of those series are fun RPGs, but they are definitely more RPG than Diablo. The worlds aren't procedurally generated, and in Divine Divinity, the enemies don't respawn. Sacred 1 and 2 are pretty beastly though.