I'm using both yoyogames GameMaker and scirra construct 2
the both engines have their pros and cons, I highly recommended if not costly to you, to get them both, you wont regard the decisions, in fact some games can make better using C2, while other will be easier and
faster to create them with GameMaker, nothing against you to use them
both for different games and purposes ;)
C2 so awesome that can make u benefit the tilesets from gamemaker, when you can import gamemaker rooms to C2.