Ok, first off, it's spelled KERNEL. There is no "a" in the word "kernel".
Now, I personally believe that Stock works the best as of right now in terms of battery life, so long as you have the correct radio and RIL combination. Custom kernels are good for over clocking, assuming you want to impress people with "good quadrant scores" and the like. But honestly, they yield a lesser battery life and higher temperature compared to stock. So if you intend on leaving your charger at home, I recommend any rom with stock kernel (ie CoreDroid, rooted Rom, Senseless, etc).