Greg - what you wanting to use it for?
Let me step out of the box just to be different. I like quads and have used them in the mountains many seasons. They are great tools and can be used for lots of things. They are a compromise in many ways though.
When the snow gets deep in the mountains they run into trouble before a good lifted 4x4 usually unless you have tracks or something. I have 37s and chains and it will take me much further than a quad in deep snow and drifts (been there done it both ways).
If you want up and down the mountain quickly and safely a 4-stroke dirt bike is a great answer. I've got a couple and can get up and down a mountain on 4wd roads in less than half the time of a quad and without worrying about getting flipped by a rut etc. You also live to tell about it if it rolls on you or you need to bail off. BUT you can't sight-see like you can on a quad.
Obviously the quad can haul more (and I've hauled out my share of elk on them), but you can get in and out of rougher places on a dirt bike and still haul some. CO even has some trail networks that are single- track only, no quads allowed.
I was just wanting to toss out something different. Quads are great, but instead of owning three, a dirt bike (thumper) and a built 4x4 do some things better and are worth having in the stable also in my opinion. They are ATVs too I guess