Mainly all mountain.
I actually really enjoy riding side mountains as to why i enjoy the traction on the slopes. Ride a lot in the rockies where it gets icy a bit.
i will def check out your other two board suggestions.
What do you mean by "side mountains?" Backcountry?
Also check out the Never Summer Infinity-r. It has Vario Grip, which is like magetraction, but less grippy. It's not as stiff as the Envi, but still kills it all mountain and comes in a 145, which would be easier for you to ride.