I'd want a switching system. Small enough that I could use it on a board so that I could adjust my pedals if I needed to. I like the POD in that I have my patches that I use and then I can turn on and off certain effects. For example I have a heavy gain patch and I can turn on a chorus if I need to. For my clean, however, I generally use a chorus in it because a clean patch with chorus is so 80's and rockin' but I can turn off the chorus if I need to without having to switch patches. 
I have yet to find a pedal switching system that could do something like that and still be small enough to use on my board. Maybe I'm asking for too much.