There are so many good ballads out there that you need to start listening, not asking. It will be like pleasant homework.
Kander and Ebb
R+H
Styne+Comden & Green (singly and together)
Kern
Berlin
Porter
Loesser
Bock+Harnick
Coleman
There are also a lot more not-that-good ballads out there. We're talking thousands. If you pick one of these and presented it quite wonderfully with a new workable subtext that's probably better than a great one presented okay.
If you want to study, any teacher is going to presume that their students have some sort of pre-knowledge of the subject. Now's the time.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher