Who do you want front and center on the cover? The box art needs to look epic for this kind of game. I think a game can say a lot about itself by how the cover looks almost like a book lol.
1st idea: side profile of Kratos on the left. side profile of Ratchet on the right. Staring each other down.
2nd idea: on the left side is all the mature characters lead by kratos. on the right side is all the cartoon characters lead by ratchet&clank.
I think it feels off because it would feel like its two teams facing eachother, you gotta make the cover show that they are all versing eachother, a character facing a character than others in the background feels like a naruto of dragon ball z game (good versus evil on the cover), i guess it all depends on the way you do it, not trying to insult your creativity , i couldnt come up with a better one, but i feel like it should somehow show that they arent really working together, they are all fighting against eachother.