People who encounter problems with battery life on Android phones tend to do so due to rogue apps more than anything. Plenty of apps and widgets are poorly coded and stop the phone from sleeping when idle and this, of course, can drain batteries like there is no tomorrow.
That said, I doubt that there is an Android phone around which couldn't be improved by use of one of the enthusiast ROMs which abound for most devices. The manufacturers have little interest on updating older phones to newer releases - Ice Cream Sandwich (Android 4) has been out for over 6 months but few older devices have any official support and many, including the Galaxy S, aren't going to get it. Samsung have spouted some bullshit about the reasons for this but the theory that the hardware isn't capable of supporting ICS is just ridiculous and there are, in fact, many very stable enthusiast ICS ROMs for this and much less powerful phones. ICS works pretty well on the crappy and cheap ZTE Blade which I bought over 18 months ago thanks to a few dedicated developers.
The fact that groups of enthusiasts (and often individuals) can produce excellent and stable ROMs despite an almost complete lack of assistance from the manufacturers indicates how relatively easy it would be to keep these phones updated with the newest versions of Android or even just produce more reliable and stable releases of the older versions. It seems too many manufacturers are just happy to hack up a barely functional release of the software (invariably adding a load of bloatware) instead of employing a couple more competent coders to do the job properly.
I'd never stick to using the stock ROM on an Android phone as I know you can improve your experience significantly with little effort.
IF this is in response to me , I have used ICS roms on my epic , all of them including the cyogan one made battery life worse.
But your basicly admiting to a broken OS and a need to fix it with custom Roms . The average user shouldn't have to wipe the phone and go rom hunting to get a good experiance on a phone . Add to that many claim the huge amount of apps on Andriod is a big plus over windows phone and yet now you have to beware of poorly programed apps?