fizik arione tri &
fizik arione tri2
They have worked the best for me during the past year.
The tri 1 is a little more forgiving and comfortable.
The tri 2 is a little tougher to sit on unless you are hauling @$$. But it is virtually flat. As I slide forward, I don't slide down. Makes me feel more efficient.
A couple of my friends love the Profile Airstryke. I rode it for a couple of months, but it was too cushiony for me.
Good luck,
Snookdude