My 'best' light, and my 'favorite' light, is an M60 in a Surefire C2-HA.
There is no question that an M60 in any Surefire host is a stunning package.
However, I'm going to go out on a limb here, possibly against the flow of popular thinking, but here goes anyway.....
I would say, all things considered, price, usuage, battery consumption, everything taken into consideration, that the good ole 6P, with the Malkoff M60L, is possibly the best flashlight available. I'm hoping that doesn't unleash a storm of protest. Note, I'm not saying it actually is the best flashlight, I'm saying it's possibly the best 'with all things considered'. Yes of course, you could start with that, then 'improve' it by going up to the C2 etc, changing it to the M60, but then other things suffer, cost, battery runtime etc.
My point is, if you're buying both, then maybe a third and fourth, you'll be happy with them all and find a good use for them, but if you really are getting just the one, and you're going to rely on it, 6P and M60L.