Personally, I like the 3rd best, but that would be expected from me right? lol, but seriously, the upgrade about to come out in 1-2 weeks is going to be totally excellent. It has ellipsoid-2-ellipsoid collision and improved everything.
The nice part about it too is that with X models and the NG dll you don't have to worry about making your geometry a certain way for collision to operate properly.
We intend to use the collision system we're designing as the base for all of our future projects. So we'll be using it heavily ourselves.
Best wishes.