I vote MP5. But another to consider may be the MP40. I rented one this weekend & it's quite a nice little gun for a lot less than MP5's are going for these days.
I voted for the H&K, but like the Thompson too. As some will remember, the Tommy gun would also fire .410 bore shotgun shells. In the 30's & 40's cops and gangsters would load the drum mags with .410 00 buck and .45 shells alternately. It was called "The Wall of Lead" and was both respected and feared. Wouldn't be many walk away from that. I wouldn't want to run into that level of fire. Would MUCH rather be BEHIND that.