Here's some great research on which submissions are finishing fights in the UFC.
The bottom line: chokes represent fully 50% of the total submissions in the history of the Ultimate Fighting Championship. Rear naked chokes account for 32% of the submission victory total, while guillotines represent 18%.
So if mixed martial arts is in your future and jiu-jitsu is in your blood, the old saw about there being plenty of tough arms but not very many tough necks remains as true as it ever was.
Somewhere Grandmaster Helio is smiling.
There's much more data worth checking out, all of it helpfully and colorfully graphed for your consumption. Truly impressive stuff. Oh, how I heart data!