What conditions will you be driving in? If its on road all the time, then I would get the LTX M/S2. Awesome tire. The A/T2 is also a good tire, but if you are looking for snow performance or wet road performance then the M/S2 will be your best bet. Although the voids are smaller, it has a ton of siping which = winter and wet road traction. In very deep snow, an AT tire will out preform the above tires due to larger voids, allowing the tire lugs to almost act like paddles (especially true for Duratracs or a MT tire). However in packed snow or icy conditions, the M/S2 will be much better than an AT tire. This has everything to do with the amount of siping on the tread blocks. Any winter tire will look very similar with tons of siping, the difference is the rubber compounds are specifically designed to preform at lower temps (and maby some studs).
LOL sorry I was rambling, I like talking about tires for some reason. What I'm trying to say is that if you are looking for snow every weekend, then you should really get a set of dedicated snow tires. The first time you hit the breaks in slippery conditions, you will realize how well that money was spent. If you cant do that then get the M/S2. It will be an awesome highway/bad weather tire. If you go off road then consider an A/T tire.
Lame video that shows the value of tire siping - posting cause I'm a nerd:
What is SIPING and how does it help your tires grip the road - YouTube