Agree with posters above that the best TD is the one you know the best. And the double probably IS the most common high probability TD for pro fighters and high level grapplers. But almost all of that subset are explosive 20-35 year olds with great technique and set ups.
But even among former high level wrestlers, attempting doubles away from the cage seems to be almost nonexistent once they hit mid late 30's. I'm thinking guys like Randy, Hendo, Yoel and Sherk come to mind (he wasn't a "high level" wrestler but had a crazy explosive double until his second UFC run in his 30's).
But for those of us who aren't pro fighters or high level BB's, IME shooting for a double vs. someone much larger and/or equal or greater skill and explosion is a recipe for getting stuffed. Something like basic O goshi or bodylock + O uchi gari or O soto gari is much easier to learn and implement by any body type.