For me it's definitely vampire Barnabas all the way. I do feel sorry for him each time the curse is reinstated, but he's just so much more interesting as a creature of the night. He is especially good in the eps from when he first comes on the show until Vicki's trip to 1795.
As others have said, Barnabas in 1967 was ruthless, unpredictable, and believably evil, yet strangely enough he never seemed more human and understandable. What was the line he spoke to Dr. Woodard? "Loathsome I may be, and evil. You can mock me for that. But leave my pain alone!"
It totally gave the viewer insight into what made this villain tick, and made us sympathize with him for what he'd been through, even as we hated his actions. That's great t.v.!