I started with the Alliante. It was OK, but on long rides (over 2.5 hours) it became very painful. I tried about a dozen others, and worked my way to the Arione. I thought it was OK for awhile, but as the miles wore on, I wore out! I got some nasty sores, and punted it. It has two seams that are in the wrong place, and it felt oddly hard. Nothing has bettered the Alliante so far, although I have an ERA Pro and an SLK waiting in the wings for testing.
2nd best was the Specialized Body Geometry Pro.
The Alliante would be perfect if they stiffened up the padding just a little bit, and took out of some of the hammock effect.