I'm not an off-roader, but lots of experience with structures. If you want strong, it seems to me that a traditional crank with a mounting spider, on the largest BCD possible, like 130mm, would be much stronger laterally than a direct mount chainring. On large 1X cassettes, that's why the low cogs are riveted together and/or to a carrier; At that large a diameter, just holding them at the freehub body provides insufficient later stiffness. For a direct mount chainring, same thing. For a track bike for racing, I could see going ultimate aero. But if you say you want strength, go large spider and not direct mount.

I much prefer 2-piece hollow-spindle cranks with external bearings, over square taper cartridges. But I bike purely on-road, and one person said they preferred square tapers for off-road, and I can see why: On external bearings, the inner crank arm face is very near the bearing seals and could grind grit against it. With square taper cartridges, the seals are well-recessed away from the crank arms, so less chance of that.