I have Shutter Precision, Shimano, Sanyo, and Schmidt dynohubs. If I can get what I want in an SP, that's the brand I go for. I have plenty of miles on Shimano hubs though, from the really cheap ones up to the Alfine hubs. On my road bikes, I like the connectorless Schmidt hubs. But you can't get those in through axle (yet?). I think I'm going to get a Schmidt fatbike hub because the SP hub is temporarily unavailable due to some issue with bearings.

I have a through axle SP hub on my MTB. The problem with that is that at low speed, my light is inadequate. I use a handlebar mounted or helmet mounted battery powered light to combat that. I think most people that off-road use a helmet light anyway. There probably are better dyno lights to use off-road, but the one i have is nice because it's really small.