Too many, depends. Favorite for:
Blasting Fun: Mac10/45 with 50-rnd magazine
Blasting Fun Runner-Up: Swedish K with 71-round drum
Impressing the Girls: 1928 Thompson with 50-round drum
Shooting Quick and Nimble: Sterling L2A3
Shooting in Rolls Royce Mode: Bergmann MP35/I
Shooting in History Channel Mode: MP40
Then there's the other side of the coin, the Most Overrated Subgun. And the clear winner is -- the 1928 Thompson. It's way, way too heavy, and the stock is way too long. If there is any subgun that is ergonomically worse, I haven't found it. The gun is also over-complicated, with its silly Blish lock, oiler, floating firing pin, and a compensator it doesn't need. On the other hand, nothing says "submachine gun" like a 1928 Thompson. Got one, wish I had six just to line up and look at.