What I should do, or who I should talk to, if I’d like to try out another branch like Air Force or Navy?

You ETS, take your DD214 to the recruiter of the branch you want and hope they're taking prior service

I don't have your answer, but, I do know that the Air Force doesn't take prior services very easily. I think the Navy is a little more open than AF but is still a little rough on it. If I were you I would try contacting a recruiter for each branch and ask about it from them and gauge your opportunity with them before you make your decision. That way you dont ETS and then regret it but can at least say you weighed your options before making a decision.

Stay Army if your current plans are to make a career. Grass may not be greener in another her branch. After you complete your tour with the Army, you would be considered prior service. This could be difficult for you...
My advice, stay Army...hooah!!