Honestly, it all depends on what you're using the media for. If you're aiming for huge worlds and very nice HD polygon counts and textures, you're obviously going to have to go for the CD. The Nintendo DS cartridge held at max a good 512MB. However, the design flaw was that the larger the cartridge size, the slower the load screens. However, the PSP had a few gigabytes of space (I've forgotten the exact number), yet the load screens were ridiculous.
The upside about cartridges are that they're pretty much indestructible if well built, and the load times are very, very fast. Well, disc based systems are starting to work on it as well, since load screens for Nintendo based disc games are very short. However, the discs themselves are very, very destructible. So, it all determined by what is to be done, but I prefer CD for consoles, and cartridge for portable systems.