Black and white, no question. I think you can convey a greater sense of mystery and dread with B&W. Just look at the Lewtons. If they were in color would they be as good? Maybe it has something to do with your early experiences watching movies. I grew up in the 50s watching this stuff on the late, late show on TV. My brothers and I would get settled into bed on Saturday night to watch the 11:15 movie on an ancient TV. We even routed the power cord to an outlet next to the bed so no one would have to get up to turn it off at 1 o'clock.