Good reviews at http://www.frostytech.com/top5heatsinks.cfm
Depends if you want to emphasize cooling or quiet.
I question their results when the Ultra 120 is higher than the 120 Extreme. Every review I've ever seen has put the Extreme ahead of the Ultra 120.
I just looked and it states at the bottom "*Heatsinks are ranked according to the lowest rise in ambient temperature on Frostytech thermal test platform"
Rise in ambient temp not lowest maximum temp of the CPU?