I don't know why I couldn't find anything about this in the forums but guys at Slash Gear have managed to get both, Android and Windows Phone versions of the HTC M8, and they're doing a very interesting comparison regarding their battery life.
So far Windows Phone performance is terrific, I believe this kind of news should get more exposed.
Source (in case you missed the link above): HTC One M8 Windows vs Android Battery Wars - SlashGear
So far Windows Phone performance is terrific, I believe this kind of news should get more exposed.
Source (in case you missed the link above): HTC One M8 Windows vs Android Battery Wars - SlashGear