Adamant. If you look at the Smogon analysis, that's what is preferred. Isn't that reason enough? :P
But, a DDing Totodile is going to be a sweeper, so Adamant will work. But, if you want more speed then power, Jolly can work too. (But Jolly would be best with a Choice set) I'd go with Adamant.
By the way, the "Ask a simple question, get a simple answer" thread is better for these questions.