I have loads of different types, TM UZI, STAR M3 grease gun, TM Mac10, Mac 11 GBB, Spectre M4 and a pretty rare Baretta M12 from the 80's (runs on a gas can connected by soft rubber hose pre HPA)
But the most fun currently is the TM MP7 GBB that I got second hand on these very forums. I've already chopped off the folding handle and fitted a A1 rail and a tightbore has just turned up so that will get thrown in as long as the FPS doesn't get silly.