I love too many, but I'll start with my all time favorite giallo (and all time favorite film) -- Romolo Guerrieri's La Controfigura (aka, The Double, aka, Love Inferno) ... Some of my other favorites include Forbidden Photos of a Lady Above Suspicion; Snapshot for Murder; Strange Vice of Mrs. Wardh; Quiet Place to Kill; My Wife, A Body to Love; The Sweet Body of Deborah; Death Laid an Egg; Deadly Sweet; All the Colors of the Dark; Interabang; The Killer Wore Gloves; and many more!