What is the strongest daisy BB gun?

If you are asking about Daisy BB guns not rifles or any other brand made by Daisy. then I would have to say the Daisy powerline models 5502 and 5503 are the fastest Daisy BB guns at 430 FPS. The Daisy 880 and several other models reach 750 FPS. But these are rifles not BB guns like you asked in this questiion.