The 747 has appeal if you are into airplanes.

But for convenience, ZRH over FRA any day. In ZRH, you arrive "clean" and only have to go through immigration before proceeding to FCO. In FRA, more often than not, you will have to go through security again as well as immigration.

The Edelweiss seat in C is identical to Swiss, the food and service are superior to both LX and LH in my opinion.