You can say "exceptional service".

Depends on the context. Could be "best service", "unbeatable service" or "top service."

You can say "top service", I think that would be fine. However I can't give more advice because I'm not sure of the context of this phrase.

Ultimate english

Hello! The word cop is slang. If you want to refer to someone's profession, you could say 'They work for the police.' If you want to use the slang word in an informal setting, you can say 'They are cops.'