Bava senior's films are something special no doubt, and his work helped me get into, appreciate, and love Italian horror cinema.
My favourite is probably
Bay of Blood (which is possibly my favourite ever slasher too), but I also have strong love for
Baron Blood,
Black Sunday,
Blood and Black Lace, and
Kill Baby Kill.
He seemed to bring something special that was lacking to the genre at the time, and as a result his work has been emulated throughout the decades.