I have yet to try out the EZVi cart, but between Acekard and SC, I do have to go with the SC on this one. Though its a bit slower, Acekard has more chances to brick itself or the card then the SC (Changing skins can cause a lost memory card, and bad kernel updates can kill a card.). The SC team is still technically new to the flash cart scene (Since they started off with slot 2 devices.) so give it some more time. The SCDSOi looks like it'll get much better much faster then the other cars can, it justs needs a few strong pushes from the homebrew scene to help out!
Plus, I actually get irritated at the OS for Acekard. I don't know why, but the actual splash screen and format is very iffy. I enjoyed the iTouch2 screens much more then the Acekard, even if its editable.