There isn't a single setup that's perfect for all conditions. For example, an ultralight setup is great for skiing the volcanoes and big tours in the spring, but it won't deliver the freeride quality you could get out of a fat/heavy setup in the pow. If you can only have one setup and you're more inclined to yo-yo for pow turns, I'd go with a heavier (freerides/naxos and fat sticks with at least 90mm under foot). The trend I've been seeing lately is dynafits and megarides/scarpa spirits coupled with a shorter fat ski (170cm-ish). That setup will rip pow/crud/mank/crust and will still be managable on hardpack/sastrugi.