I mean, a little of both would be fine. Star Trek is mostly about the characters finding optimism in the face of pessimism. DS9 can be dystopian at times, but the characters sell the optimism which guides them through the danger.
So, I would love to see a combination, which is in line with the ethos of the show.
An entirely dystopian Trek would be fun as a limited miniseries, but it would eventually get tiresome. Pure dystopia has been done many, many times before, and that's not what we come to Trek for.