Mine was the PS3 which is surprisingly easy to modify and their ps1 and 2 emulation works really well. It’s a nice little box if you can pick one up.
I've been looking for one which can play SACD's and has the hardware emulation, they're actually a bit rare.
The launch model PS3 is a beautiful thing. Four USB ports, lots of card slots, hardware PS2 compatibility, plays Blu-Ray/DVD/CD/SACD... and that cool Spider-Man 3 typeface.