Tom and Camilla - but I've had other favourites for brief periods throughout the series:
Mark and Hayley when the couples were announced
Austin and Erin after the preview show
Cherie and James after their rumba
Jodie and Ian after their waltz
Heather and Brian after their salsa
John and Kristina after their waltz
None of these lasted very long - by the time each couple was eliminated I'd already switched to another couple

But my TomCam love is the real deal; it's the first time I've been truly excited all series.