Just giving my opinion.
For me gravity nymphs are the biggest problem, since I play rainbow decks and quint my creatures. I either use a pulvy or a reflective shield so the air nymph is less of a threat aswell.
So I'll repeat myself:
> > > rest
u use rainbow and quint? in FG fights or just all of your matches?
cuz' rainbows with quints might be too slow for PvP, unless it's a stall, and if it's a stall, gravity will give you the most trouble, but air should give you the most trouble, since she can bypass most shields, and thus you can't really protect yourself with shields