Barnabas was never better than in 1967 - I really wish he hadn't been redeemed so much, as he seemed infinitely more interesting in his earlier, uncontrollable form.
The problem with the added humanity was that it robbed Barnabas of so many facets, and nothing seemed to emerge to replace all those lost qualities. In the early days he's intelligent, resourceful, plausible - things that give a villain a real sense of danger. Even Julia doesn't come close to controlling him - he's very much in control and what always disturbs me is the ruthlessness, you really believe he'd stop at nothing to get what he wants.
Those insidious qualities really do make him a cut above other DS villains - others require characters to develop selective stupidity while plotting and vying for control. In 1967, Barnabas didn't need that - the really scary thing is that people in Sam and Joe's position wouldn't have suspected him for a moment in real life.