Not sure they have to make that choice. They won't be giving up either Patton or Cameron to acquire Tippett. They'll either give up one of their draft picks, or will just take him for nothing in the draft (which they might have to if Tippett doesn't agree to be traded to GWS).
Promising as they both look, they are physically 3-4 years away from being able to hold a forward line between them. Tippett would add support, attract the best defender, and also provide relief in the ruck.
Depending on how they've structured their salary cap, Tippett would make a lot of sense for GWS, apart from the fact his selection of Sydney as his preferred club suggests he doesn't want to be playing with a cellar-dwellar for the next couple of seasons.
If GWS can engineer this (and particularly if they can persuade Tippett he wants to play with them), good luck to them. They are certainly in a far better position to satisfy the Crows trade wise, and it will be less tedious for the rest of us the sooner they can become a semi-competitive side. Most Swans fans acknowledge that Tippett will improve our list but I suspect most will be nonplussed if we don't land him.