PlayStation makes the most sense to me. You can play PS1 games on a PS3, you can buy them digitally on PSP and PS3 (and Vita and PS4 for all I know). A lot of them have gotten released on other systems in one form or another. And, many, many people have interest in playing at least something on the system. Everyone likes Metal Gear Solid and Resident Evil 2 and Mega Man X4 and all that. Dreamcast and TurboGrafx games might be harder sells. Of course it's also massive and has like 90 versions of every sports franchise, so I dunno.
Just my 2 cents.