You mean the VCD card. The best one, supposedly, is the one that came pre-installed in some of (all?) the HiSaturns. This is also the hardest one to get obviously, because it tends to stay in the machine. This isn't the Car Navi one, just the regular Hi Saturn. It doesn't play Photo CDs, but supposedly the video quality on VCDs is better.
The only one to outright avoid is a sort of brand-free Chinese POS, which you'll probably never run across anyway.