The Challenger 8 is HOKA's road-to-trail workhorse, and the 8 adds what crossover runners actually use: more foam underfoot than the 7, an improved fit, a rubber toe cap on the minimal mesh upper, and multi-directional lugs re-oriented for ground that keeps changing under you.
It suits you if your running mixes surfaces — gravel grinding, park paths, the road out to the trailhead — and you want one shoe that never feels wrong on any of them.
It is not a technical trail shoe: when the ground turns to rock and root, the Speedgoat's grip and protection are what the Challenger deliberately trades away for its road manners.