Cho'gath is already strong, not broken, but sitting on the fine line known as being "balanced", having high damage and CC, but having two spells be melee range and one be an unreliable skillshot. He has high sustain, but has to get in range of poke to do it.
Of all champions, Cho is in a good state as is, and requires no changes.
Give the guy a break. He has been competitively viable for all of two patches, is heavily skillshot reliant unless fed beyond belief, and is completley immobile.
If you want to nerf him, just revert the reliability buff to his W.
But whatever you do, DO NOT TOUCH HIS BURST. Veigar is THE burst mage. Even when he was weak as hell, he still had that. I thought we had learned NOT to nerf a champions core identity from what happened to Kassadin and Sona.