Don't forget about Game Cube compatibility, I'd take the GC library over the Saturn's (especially those readily available). Of course you could go with a GC for a lot less, and they're pretty solid in terms of reliability, though only early models offer the digital out port for component video -and 480p support. (a plus for Wii is it supports component and VGA on all models) Plenty of GC titles still exclusive and without good emulation or ports. (emulation on saturn is pretty iffy, but some of the better games have been ported)
Of course the PS2 is generally a better option if you never got one, but It's a lot more lkely for someone to have passed over the GC than a PS2. (there's DC of course, which is worth getting as well -though a fair number of ports including SA1/2 on GC, Xbox as well, but not as varied of a library as GC -for some reason I favor Xbox and GC over PS2 though, I'm not sure why other than the controllers -I like the duke and the GC controllers don't care for dual shock or s-controller on x-box -some 3rd party PS2 pads are OK)

