+1. The Illusive Man is just the awesomeness of Martin Sheen's voice. Mass Effect 3 ruins everything they had built up for him in ME2, and in my mind disqualifies him for any all-time list. Still one of the best voice-acting jobs ever, though. ›››
It wasn't just his voice, it was the theme song, visual design and general presentation with him in his office.
A perfect example of presentation hiding the fact that a character isn't worth shit if there ever was one.
OT: My biggest gripe with Saren is that at no point does his motivation of trying to appeal to the Reapers sound even remotely like a good idea. The whole schtick of wiping out past civilizations, the sadistic huskification process and Sovereign's(and by extension the reapers as a whole)general contempt for organics as lesser beings don't sell it.
Still, him and Vasir win by default as ME's best antagonists given how god awful the rest were.