Boohoo nobody mentions Bioshock.
1. Mass Effect
2. Bioshock
3. Uncharted
4. Portal
These are all great franchises, I'm not sure I what the 5th should be, but Infamous (no franchise yet), Assassin's Creed (bad first game), Motorstorm (2 good games, 2 bad) would make a chance.
I understand that's it's about IP and not franchise, but I prefer not to put a single game in here.