Yeah, MagiC64 is the best option for 680x0 users. Nice and fast, and reasonably compatible. On my old blizzard iv 50mhz '030 it was quite usable. About 90% speed when skipping 2 out of 3 frames (which is actually more playable that it might sound). Disabling sound will result in a decent speed up as well.
On my current 40mhz '040 it's full speed with sound using only 1 frameskip and the occasional game will run pretty much full speed without frameskip.
An '060 fill give full speed/framerate for most games.
I did try it on cd32+sx-1+fast ram some years ago and it ran pretty horribly unless screenmode is set to 1bit color, which made a huge difference. I could even play c64 buggy boy at an ok-ish speed, even if it did look a bit spectrum-esque
Ultimately though unless you want to use 1bit color forget it unless you have at least a fast '030 + fast ram. Much like the amiga a c64 isnt the easiest machine to emulate and requires a lot more power than other machines of it's era.