For some reason it's the Delaware River - the one between Philadelphia and New Jersey - that gets all of the attention as the place where there should be awesome stuff. But the Delaware's really a big ugly river. It's the Schuylkill that really has the potential to be a lovely riverfront. It is already in places, but the highway ruins the most central bits of it.
Both rivers have access destroying highways. There's I95 on the Delaware and I76 on the Schuylkill.
No need to choose. Knock them both down.