Reinterviewing post-SA

If I interviewed with xyz firm for an SA position but didn't get a summer offer, interned at another bank (abc) and got an offer, what is the process with interviewing again with xyz for full time?

I'm wondering how to put this across in my cover letters, i.e. how to say "i got an offer from abc with rave reviews, and i loved my firm, but i liked xyz better from the start, and i'd get a better analyst experience at your firm modeling-wise"??