I use quite a mix of pencils, mostly Prismacolor/Karismacolours, Caran D'Ache and Faber Castell's Polychromos so I can only comment on these. I think out of the lot, my Caran D'Ache ones are my favourites.
I find the prismacolours a little too soft and waxy and whilst I really love my Polychromos ones (I only have a few) I sometimes find the leads a little too hard and so they don't blend as easily as (say) the prismas. But the Caran D'Ache ones seem to be totally in between. They're not the cheapest of pencils (but as far as I know they're less expensive than prismacolor) but I have a set of 18 and that is absolutely plenty of colours to use for any picture.
They are my favourites because the leads are soft and blendable enough to be easy to work with but not so waxy that it shows up on the paper, and the leads also seem to be strong enough to resist breakage (I've dropped my pencil roll with them in from short heights and they're not suffered any ill effects as far as I can tell, which my prismas have). And the colours in the 18 set seem to be a good enough range that I don't really feel the need to purchase a bigger set.
So hopefully this might help you a bit