I would guess sitting idle doing nothing, the differences would be negligible.
I think you would see marginally different gaps by using various kernels. Some are geared to better handling wakelocks and shutting things down to a very low state while idle. But, end of day, I would wager a difference of maybe 30mins, if there was one.
Andreilux, the brains behind the perseus kernel (tw roms only) could give a much better insight on the edge cases and why/how drains happen outside of errant apps. But most mere mortals may go glassy eyed trying to follow along.
I would love to help you, but help yourself first: ask a better question