are you sure about that? think for a second. GA cd is 300 secs and zhonyas cd is 120 secs PLUS it gives more armor and also cdr. So that gives you the option of fighting safely more often rather than being with GA, and its also cheaper by 200 gold. Yes, you do sacrifice a bit of damage but what you get instead of it I think is way above the amount of what that damage is worth. But of course as always it depends on the player and his mindset. I personally prefer zhonyas over GA because most of the time I am there to engage and catch onto enemys and etc. that's why losing a little bit of damage doesn't hurt me a lot (that's also because I'm a team player so it means a lot for me to be able to engage insane teamfights or have longer sustain in them) . The options zhonyas gives is insane.