Eh, how long it’s been on TV doesn’t necessarily equal amount of content; in that case, TTG had EEnE beat long ago, and it’ll take another season before it beats Adventure Time on that front:
Adventure Time - 70.75 hours
Teen Titans Go! - 68.25 hours
Regular Show - 66.75 hours
The Amazing World of Gumball - 60 hours
Steven Universe - 46.5 hours
Justice League - 45.5 hours
The Powerpuff Girls - 43.25 hours
Ed Edd n Eddy - 42.5 hours
Codename Kids Next Door - 42.5 hours
The Grim Adventures of Billy & Mandy - 42.5 hours
Dexter’s Laboratory - 41.75 hours
Foster’s Home for Imaginary Friends - 39.5 hours
We Bare Bears - 36.5 hours
Johnny Bravo - 35 hours
Samurai Jack - 31 hours