The best for me is M/F, M/FF, or MM/F. Sometimes i like F/F too, but rarely. I mostly like a neutralizing situation like the guy being much younger than the woman but able to cut her down to size so to speak, because he can tickle dominate her.
One of the reasons I like MM/F and M/FF is where the tickling is not equal. Such as the one M is a better tickler than the other, or the one F responds more to the tickling than the other.
In fact, I think there is a shortage of good MM/F or MM/F tickle videos out there. If you know of some good ones, please share.