I'd probably go 60GB PS3 with hardware emulation for PS2 - unfortunately the PS1 emulation is software so it wouldn't count.
Close second would be the SNES. It's top games are the best IMO but the sheer volume of good stuff for PS3 and PS2 just kills it.
If I only had to keep one console with emulation allowed I'd go Wii because it plays GC games, and can be easily hacked to play NES, SNES, Genesis, TG16, GB, GBA, GBC, etc.