Most bad***** serve from the old school, I'll go with Tanner.
Of the newer tech rackets, take your pic out of Karlovic, Isner, Raonic, Ivanisevic, Roddick, basically any of those guys that can unleash hell in the 130s like it's no one's business.
Roger Federer. Paolo Maldini. Tom Brady. Wilt Chamberlain. GOATs.