E/ME in PvP, which element?

I'm uncertain which of two elements to use, air or earth.

Air has a lot of 25% piercing spells, but causes a lot if exaustion.

Earth has 2 100% piercing spells, and it has a lot of defensive spells, but it seems to be much less popular.

What do you suggest? Give motivation please. Thank you!

Air is popular so people know how to defend it. Earth isn't, so you may catch people by surprise.

Personnally I'd say air as they are always in demand. However, you should have both so that you can swith skills and attributes depending on your mood and gamind style

Have one or two good deffensive earth spells on hand but be more air.

off topic question,
so fire is practically useless in PvP ?

Fire has too many long-duration AoE that people can easily get out of to be as effective as the other trees.