All other things (ie the rim, the lacing and the tension in each spoke) being equal, the spoke type will make practically zero difference to the stiffness of the overall structure.
But for an MTB wheel with disc brakes (indeed any MTB wheel) you have to ask whether the weight saving is worth the expense, the slightly reduced strength, and the fact that they’re harder to build a good wheel with. Unless you’re well practised at wheelbuilding, I would suggest sticking to Comps. And I would definitely use Comps (at least) on the rear drive side even if you have Revs everywhere else, because they’ll be carrying rather more tension than the others.
Don’t forget, too, that Revs come with aluminium nipples, which are less reliable than brass ones and are more likely to round off if you need to true the wheel after they’ve spent a couple of wet winters binding to the spoke.
Personally I stick to Comps for anything but my summer road bike, they just work faultlessly and they’re easy to build a good wheel with. Revs are only worth the bother and expense if you’re a real weight weenie.