I don't even think I could name my top 5, or at least rank them in order of 1-5.
my favorite overall horror director is probably Polanski. The apartment trilogy (Repulsion, Rosemary's Baby and The Tenant) are just fantastic. Out of those 3, Rosemary's Baby would probably be in my top 5.
I really, really love Possession (1981) and would put in in my top 5. House (1971 Japanese horror flick) is just so damn amazing and weird, I rewatch it regularly and would also lump it in my top 5.
Top 10 I'd throw in some classics like Texas Chainsaw, Wicker Man and The Shining.
seen em.