I've been using CyanogenMod for a while now and 6 is the best release yet.
Jeagoss writes "CyanogenMod is the leading open source replacement ROM for Android based phones. With the 6.0 release, a targeted 8 models of phones have been hit with version 2.2 (Froyo) of Google's Android operating system for mobiles. Have a rooted phone? Been wanting a reason for rooting your phone? Head on over to http://www.cyanogenmod.com/ and check out the forums. I think you'll be quite surprised."