I know some wag will say McDonalds or Argos, but I'm thinking more of TV and film franchises. Which are you favourites? And the ones that leave you cold?
For me, the best is probably Star Trek. A classic original series, a very good follow up series, and a few good films. Including the cracking recent reboot. Sure, they've had some duff moments, but overall it's a pretty impressive body of work.
The worst for me has to be Stargate. The film was so-so, but God knows how it managed to give birth to so many series. Oh, and Harry Potter does nothing for me.