Depends on your sound. If your're a Trap/Southern producer; of course DJ Paul & Juicy J (the basic template to all trap production), DJ Squeeky (EXTREMELY underrated legengary Memphis producer), Zaytoven, any producer on the TM 101 tracklist, Mannie, Southside, Metro, Lex Luger, ect. But don't just listen to hip hop producers, branch out and listen to producers of other genres, especially R&B. Many R&B producers have a lot more musicality in their work than hip hop producers