I don't see why doing both isn't an option. However, if you must choose one...
If time dedication is not a factor, going back to school is probably better. In the long run, it may even end up being the cheaper option. If time dedication is a factor, then the choice is obvious.
On a side note, lots of things can "beat" a degree. Experience. Networking. Expertise. Self-employment. Just to name a few. Similarly, a degree can "beat" those other things too. Neither one of these things are necessarily better, but they are helpful in their own way.