I just went from my stock avenir, which wasn't too bad actually, to a Selle QBik. Its a little thinner and has a little more give. Plus it has the cut out. I almost went with the WTB model that people really seem to like.
old one
http://www.amazon.com/Avenir-Series-...rds=avenir+200
new one
http://www.amazon.com/Selle-Italia-Q...le+italia+qbik
option 2
http://www.amazon.com/WTB-Speed-Bicy...rds=wtb+saddle