When it comes to actually hitting the pavement GaGa is relentless, there was this graphic someone made with all of GaGa's promo outings for her Born This Way singles, and it was a lot. Not to mention all her random endorsement tie ins in the beginning of the BTW era.
But when it comes to tactics, Katy doesn't give up. But still throwing someone on a remix, and calling up Itunes to reduce the price of a single, is far less work than trying to perform on every TV show known to man. So I give it to GaGa.
In the end, Katy's have proven more effective as of late.