There you have it, folks. The strongest is not Goku. The strongest is not Superman.
The strongest animated character ever is Saitama, from One Punch Man:
See, One Punch Man's sole purpose of existence is to make fun of the Superhero genre in the USA for how strong the country makes its characters. Saitama, in his entire existence, is a joke. He defeats, nay, kills any enemy of his with one single punch, every time.
Supes and Goku, their characters at least try and have a little logic to go with their backgrounds. One Punch Man has
no logic; it's One Punch Man.