Lots of similar threads around.
Seems to me what is really useful to know is the current drain during standby (as logged by current widget or other similar prog). My opinion at least is, when you're using the phone to do stuff, it's gonna drain battery at a rate depending on what you're doing and how fast you're doing it, so that has little to do with the ROM. But when the phone is in standby for the other 10 or 20 hours, if it's draining 300ma or 3ma is what makes the big difference to battery life. I'm seeing 2:1 differences just by putting a different radio in! And as far as I'm concerned, stock, insertcoin, ARHD, whatever... any one would be fine feature wise, but it's much more important to me to have a phone that will last a full hard day without a charge. And a 2 day cycle would trump all other details. So I'm experimenting with different ROMs, kernels, radios and RILs to try to find the magic combination.
And BTW, FWIW, so far, ARHD with Bricked kernel and recommended radio seems to be best (at about 40ma), and I've seen a lot of others reaching the came conclusion. But I remember reading a thread where a guy was showing 1 to 3ma! (it wasn't a sensation though, but an HTC of some sort), so I think there's room for improvement somewhere!
See this thread also:
http://forum.xda-developers.com/showthread.php?t=1254127