I think the simple answer is to ride a few and see.

I detest soft boots, but I've ridden the Kyhber and lots of Fish using
proper hard bindings. The Kyhber feels (and is, as I rode it) longer
than the Fish and less dedicated, but it's still basically short and
turny, as opposed to big and cruisy. So you trade acceleration and
possibly stability at speed for agility in the trees. Most people get
the thing which works where it's toughest, hence the popularity of the
Fish in serious powder. But these are pure powder boards: I wouldn't
consider riding either in bumps or on hard piste. Of course it could be
done, but I wouldn't do it.

For piste stuff, you have the same choice (turny or cruisy), but you'd
be considering a different set of boards. Here it's more "do you want
to be the absolute fastest on the hill, or do you want to ride bumps".
Pick a board designed for one or the other.

I think you might want to figure out first how many boards you're
prepared to carry about with you. If you can stretch to two, then it's
easier because you can have a powder board and a piste board...