I've got an ipad Pro with keyboard and it's great. Depends what you plan on doing tbh. Also got a mac book pro. Used that for uni work, use the ipad more for browsing / reading
Entirely depends on what you wanna use it for, and personal preference.
Personally I don't like using a tablet as anything more than precisely that, and I've got one that I never use, so it'd be the Air for me all the way were those my options.