I like the masterminds with vision, where they either think they're doing the right thing but are willing to bloody their hands a bit for the glorious utopia that will ensue, or they know they're a monster but willing to do evil to see a glorious future. The kind of guy you respect for their convictions but can't abide by their methods. Bonus points if their arguments actually have merit. (I should point out while I love this character type in fiction, in real life people like this are always bad news.)
I don't mind the occasional one-dimensional psychopath with a colourful schtick, but I prefer them as henchmen or lieutenants rather than the main threat. Yeah, I watched a lot of Bond movies in my time.
I also like the villain who isn't really evil, or at least didn't start out that way, but was screwed over in some way by society or the "good guys", and was convinced to join the villain's side. That allows for good character development, I find.