I would lean toward finishing your PhD, but it depends on what you wan to do with your life. Remember, you are frustrated now with academia but the Army always looks better when you are a prospect than when you are a customer.
lol...that is true.
Just another thing to keep in mind, as you say "it's now or never" but school will always be there.
Do OCS and finish your PHD while there. Let us pay for your education. It is well worth it.
Finish the Ph.D. In the long run, there will be more opportunities out there for you. Can you go to OCS after finishing? Still many things you can do with a Ph.D. in the service.