ORIGINAL: Dili
My list is just to have open options and represents my knowledge at time. Right now i have found for example an ME110 employed in North Africa that had a 30mm gun and i have to check numbers built and it's representativity.
That would be the later types of the Bf 110G (-R3 and -R4), armed with two MK 108 30mm cannon. Be aware that those guns had short barrels, leading to low muzzle velocity. Good for ground attack and against bombers (if you got in close). Less effective against fighters.