I would certainly try to avoid debt if you can if you plan to major in music theory.
The tradeoff between “quality of program” and “amount of debt” is tough for me to judge. For us (mostly with different majors) the higher quality programs did not generally cost more and might in some cases cost less. We might have been lucky in this regard.
What is your home state? What schools are you considering? What can you afford without taking on debt?