Without the addition of a video card the Magic 64 is the fastest with an 060 but you won't get full speed without using some workbench patches (fblit, blazewcp etc) and you will need frameskip too. Real sid won't work too well either.
It's also not 100% compatible and some games will suffer with glitches and others just won't work.
Frodo V2 can run at a decent speed with the right patches and settings with a frameskip but again it's not 100% compatible.
Your best option is to get a C64
