I absolutely adore all 3, for different reasons.
SCD - LOVE the Pros Dancing, and their personalities.
SDF - The first series was totally gripping [and Katie, from Alex & Katie, the Tango couple] came on a forum I was posting reports on and was soooo sweet.
Also LOVE Graham Norton.
DOI - As a T&D Fan of 27 years, I was soooo excited about this show. It was a huge improvement on the BBC's Strictly Ice Dancing one off show, very professionally produced, and I know one of the Pros, Marika, so got the backstage gossip via email, which was fab.
Am gutted she can't do series 2.
All 3 formats have been huuuuuge hits around the world, so YAY for the Brit TV formats!

The latest one is Maria - currently in the States with Denise van Outen presenting, searching for 2 stars for Grease.