Looking at getting into mountain biking. I ran cross country all of middle school and high school. Ran in college but not for a school. Now Im a school teacher and wanting to get into a better sport than running. I have a budget of 600-700 ish. I have looked at the Trek X-caliber 6 and 7 along with the Cannondale Trail 6 and 5 29er. Wondering which one should I get. Any advice would be great.