I'd say 7/8" is the most common... you can usually make them fit with the offset and/or bending the latch thing if it's not the right size. 1 1/8" also usually works (same thing w/ the offset/bending), but I've found that sometimes they're too deep and hit the coin buckets. Nintendo cabs are the only ones that I can think of that use the really shallow ones (5/8" I think?).
DogP