My favorite is the Bigsby, but the only other one I've ever tried is a Floyd Rose. I much prefer the Bigsby to the Floyd.

But what else is out there?

Also... my concern is about how a tremolo might (negatively) effect such things as sustain and tone.

Which tremolo diminishes those things the least? Which one's the worst for that?

Which tremolo has the most... uhhhh... ease of use and variation and the least loss of sustain/tone?