The three non-cannon couples I remember rooting for as a kid are Dale/Gadget (Rescue Rangers), Baloo/Rebecca (Talespin), and Velma/Shaggy (Scooby Doo). I can't remember which came first, so I'm including all of them.
Dale and Gadget:
( Dale and Gadget )
Baloo and Rebecca:
( Baloo and Rebecca )
Shaggy and Velma:
( Shaggy and Velma (again) )
Dale and Gadget:
( Dale and Gadget )
Baloo and Rebecca:
( Baloo and Rebecca )
Shaggy and Velma:
( Shaggy and Velma (again) )