Given ONLY those two choices, i would get LTX M/S. But, if you can go beyond those two Michelins but still say within Michelin brand, then i recommend LTX A/T-2 for your needs.
Do you know how does the A/T-2 compare to the Cross Terrains in therms of mpg and ride quality. I understand the ride is supposed to be a little bumpier and the mpg somewhat worse, but to what extend?