Aether trumps Frost damage type in almost all respects:

-Aether works against everything, including super bosses and unstoppable enemies. Frost is useless against such enemies.

-Aether has stacks thus allow Wisdom builds whereas Wisdom is utterly useless in Frost builds.

-Aether has much better PST support. With nodes from Abyssal Shaper and Timeweaver you can easily exceed what you would get from White Arrow and Oracle of Trinity in terms of damage.

Frost needs to somethings else (have some sort of stack effect or do something against super bosses) to be competitive.

Thank you for reading my feedback.