What is your opinion on the best tire in the snow for X's? I have a 2wd and frequent the mountains in the winter and want to get better traction next winter.
Best snow tire for what?
Mud-terrains actually do pretty well off-road when it comes to driving around on mountain trails in deep snow. They tend to do poorly on pavement or smooth surfaces, though, since the smooth lugs give them all the traction of a racing slick. Some brands (Pro Comp) put sipes on the treads to make them a little more bearable to drive in the wet or snow.
Quite a few All-Terrains (BFG AT, Bridgestone Dueler A/T Revo, etc.) do VERY well in the snow in on and off-road conditions, the BFG AT is even snow-rated, (although reports have it it's snow-going abilities fade with increased tread wear).
There are even All-Season on/off road tires that lean more towards highway driving (Michelin LTX M/S), that give the mileage and all season abilities of a highway tire with quite a bit of the traction of a snow tire.
For pavement driving, though, it's hard to beat a typical dedicated snow tire from one of the major manufacturers, since the softer tread compound is made to give outstanding traction in the low temps and slippery conditions typical of winter driving. Goodyear, Michelin, etc. all make snow tires in SUV sizes.
Personally I just use the Michelin LTX M/S, and when the conditions exceed the abilities of the tire, switch it to 4WD. If conditions were such that even 4WD wasn't doing it, it's time for tire chains.
I'd say the BFG AT might be the choice for when you do more off-roading than on, or just want an AT tire on your ride.