I thought i'd just point out that just because a dragon might be Super Rare, doesnt mean it costs alot of food to feed to epic. If you have any of these, i would feed them to at least level 9. FYI there is often little to no difference between the strength of a lvl 9 and epic.
If i had my time again, i would raise 1 of each colour combo to level 9.
Blue/Green - Atlantis/Mermaid
Blue/Purple - Aether/Mistmoth
Blue/Yellow - Clown/Storm
Green/Yellow - Parakeet
Red/Green - Forestfire/Landworm
Red/Purple - Planet
Red/Yellow - Honeybee/Scorpion
Pink dragons like Lightning, Divine, Lacewing or Marshmallow are great in battles too.
If you have Gemstone dragons, i like Ruby the best in battles (although it was one of the last i raised fo epic)
And of course Diamond once you get it then its hybrids