I want to wear some bold colors contrasted with a dark black. Which part should be black, and which colored?
I really like the look of the black jacket + colored pants, but I don't think its efficient to buy more pairs of pants than jackets. It seems much more versatile to have a pair of black pants and a bunch of options for jackets...
My 2 cents, go with black pants. I think its easier to have a nice pair of black pants and then if I want a different look I have a few jackets that all look good with them as well as hoodies if its warm out, you might get sick of the color otherwise. Also the pants get dirty quick, black will look good longer.
I also like the black+color combo. As snowklinger said, black really makes the other colors pop. I also like that I can pair anything with black, so when getting ready in the morning (or even when shopping) I do not have worry about whether the color(s) and/patterns match or clash.
But I prefer black pants with a colored jacket. I think of pants as my 'serious'/workman item of clothing (needs to be able to take plenty of abuse and be really waterproof) and jackets as something to have fun with. Also a brightly colored jacket makes it easier get spotted (both in the trees and among the crowds around the resort runs) and I am wondering whether a black jacket would be too hot on the chairlift on a sunny day (not a problem for me - I am always cold...)