I liked Titan Quest, but I didn't love it. Only ever completed it once. It's definitely an ARPG and if you aren't into that type of pure combat game, it won't be for you.
Never even got Sacred 2 because of the abusive DRM, but Sacred 1 was solid enough, if you like ARPGs.
Neither is a match for Diablo 2, mind.
What exactly is Diablo? I love RTS/RPG games but if it is just a game about hell and the devil, I think I will pass.