Reason why Cho'gath is unpopular
He is super clunky. SUPER CLUNKY.
His Q is very telegraphic to the point where, unless the enemy walks into it or the target is already cc'ed, it is useless. You also can't cast anything during the cast time of q or cancel it or anything if you press the button you are forced to wait a long ass animation before you can do anything.
W's hitbox and visual effect are completely unrelated.
E is same as W.
R is a decent ability except very unreliable. Also having execute on a champion who is mainly played as a tank is very weird.
Seriously we should stop releasing new champions for a bit and focus on reworking these older champions.