Formula hubs are decent. Gran Compes are definitely a little nicer when it comes to their finish, they may be a bit lighter (definitely lighter if you go with the low flange ones), and are more commonly available with fixed threading on both sides, which is a plus IMO. They're going to ride about the same though. Hubs don't really have much appreciable difference on how your bike feels and performs on the road as long as they don't have junk bearings.