Sega CD for me.
Sonic CD was good, but I could get that on Sonic Gems. The RPGs were out of my price range. And the shoot-em ups, while good, weren't as good as a lot on other systems (except for the stellar Lords of Thunder, but the TG-CD version has a better soundtrack). The FMV games were a good laugh for a minute, but they got old real fast. My Sega CD really just collected a lot of dust most of the time, until it finally stopped reading discs.