I'd go with the cross check for several reasons: versatility-gears, large tires, fenders, racks etc. Also, you will want the fat tires. If you're doing any actual mountain biking on it you're gonna want the 45s. Sure, you can ride trails on 30s or 35s but you'll be much happier with the ability to run something larger.
Definitely a no-brainer.
B
Definitely a no-brainer.
B