I think I very often use the riffle force. I am also a fan of the turn-over-force, which I don't remember the original name of (it's on the Sankey series).
I like the back slip force (its the first one I learned and may well be the same as the slip cut force), the Hindu Shuffle force and I am trying the overhand shuffle force now but I am a bit clumsy with it still when I get up to 4 cards.