Congratulations on your choice to serve, no matter which branch you ultimately choose.
My answer will be as biased as anyone else's, but I would suggest the Army over the Marines, for the simple fact(s) that: The standard enlistment term (Active Duty) is one year shorter, there are a larger number of jobs to choose from, there is more money for college after service and there are more possible duty stations (Embassies not counted).
Beyond that, both services offer great training, pride and an ability to grow and stand on your own two feet.
If college immediately after high school isn't for you, the military is a great choice.
PS: College is no longer a guarantee of anything, except piling up massive loans that have to be repaid eventually.