CCS64 and VICE are the best.
CCS64 is the best of them all, its weakest point being sound emulation (quite shitty, being worked on!)
VICE emulates the 64 as well as PET achines and the 128, and its best point is sound emulation, because it uses the brilliant reSID engine.
Make your pick
Frodo is fast as hell, I used it a lot for making programs and store them in a dir of my HD as if it was a C64 drive (that's its best feature, I think VICE does it too)
(nice program there meegaboy