Stock ROM Battery Life is really bad. Stock email for IMAP on multi email accounts issues duplicate emails and email sync is bad.
CyanogenMod Version 7.1 Awesome ROM lots of features stable and good battery life. No issues with email. Fast reboots.
Android Revolution HD 4G Version 6.3.2 Great ROM but I see no difference in the battery drain from the use of HTC Sense. Email for IMAP on multi email accounts issues duplicate emails and email sync is bad.
RCMix3D Version 4.0 Good ROM lots of features but takes too long to load with ROM developers screens. Battery life seems better than Stock ROM. Email for IMAP on multi email accounts issues duplicate emails and email sync is bad.
So far I will stick with CyanogenMod for the stability so far I have seen.
Plus I have order a new extended battery to help with battery life.
My fav is Android Revolution HD. I am still on 6.3.2 since 7.0.x doesn't appear to be fully functional. I like it because I like Sense (I know, I'm not sure what's wrong with me either). I'm anxiously awaiting the DHD's ICS upgrade so we can get a ROM built off of that.
My favorite ROM would have to be Android Revolution HD 6.3.2. Sense 3 is great and more functional than the stock ROM.
Currently, I am using "Redemption" by The Collective team. It's based on the ICS AOKP source, and it's been working for me with few problems. One may complain about issues with garbled text, but a reboot is all that's needed to remedy that. Much better battery life than Sense, and it's highly customizable.
Cyanogenmod 7.2 RC1 for me. It's quite stable, performs solidly, and allows me to optimise battery life nicely without sacrificing performance. I'd say I've had roughly an 80% battery life improvement over stock.