Get your BA in Jazz. Get your BA in anything if truth be told. Your degrees will help get you your first job and while they will help in further jobs, the degrees will help less the further out you go. YOU will make yourself marketable in the job interview, not all the degrees in the world or a high GPA.
That said, this year and next get as many classical courses under you as you can. Classical will give you the technique to segue into musical theatre. Jazz is a much harder transition and you would probably have to 'travel through' classical anyway to get to musical theatre.
(The same logic applies to dance. Take ballet first since everything including body awareness seems to come from it. This is my own theory, but run it by some people. Get the technique and then move outside the circle.)
Jazz will give you wider interpretation boundaries so you can give each phrase a subtext. You have to have a reason to sing each song you sing. This reason can be in the text or in your head and heart, but there precious little that is duller on stage than someone singing a song for no reason. Make the material your own.
Don't forget acting either.
Whatever you do, have fun. If you're not having fun, what's the point?
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher
