The classic force if you can pull it off, but since I don't hit with it all the time, I use the riffle force most often.
What I usually do is try to classic force a card a few times with a force-required trick involved. If I hit, I do the trick, if I miss, I do a different trick where I don't need to know the card (the biddle trick is usually my fallback). Then after I'm done with that I'll riffle force the card and do the trick I had intended to do.