This is tough, because all directors study Hitchcock, and I can confidently say he's a master of suspense.
I remember watching the birds for the first time as a kid and being legit shook. I remember the highschool film and literature class discussions we'd have about Psycho and the techniques and angles he used to tell the story. It was deep shit. Hitchcock is really the legend they make him out to be.
But I connected and felt Singletons work much more.... His first three movies were a major part of my childhood in the 90's. Their soundtracks were the soundtracka of my teenage years.
The personal bias is too strong.... I gotta go with Singleton