I've been playing on PBE. Water and wind dragons bring the most enjoyment to the map. Meanwhile, mountain and fire leave much to be desired.
Mountain dragon doesn't give any interesting mechanics. The walls at the dragon pit mean nothing unless you are waiting for the next dragon fight. And putting them at little intersections is more aggravating than fun. At least the grass overflow comes with healing plants to make the jungle feel more lively and fun.
Fire dragon is even less interesting. Breaking apart the buff camps, I know you're trying to "open" each jungle quadrant, but it didn't feel like much was changed.
I can't explain it, but those two dragons lack the "oomph" factor.