I enjoyed watching all of Thayer's characters, but the three that I voted for are Prof. Stokes, Ben Stokes, and Count Petofi. The professor is my favorite character but I think Ben was his best character on the show. Not only was the coarse servant a complete reversal from Thayer's sophisticated professor and count, but as stefan mentioned, Ben Stokes was very authentic. Thayer always stayed in character and made me believe in the reality of Ben Stokes; the character seemed like a real person, not just an actor delivering lines. It was enjoyable to see Ben grow from being bitter and vindictive into someone who was loyal, compassionate, and self-sacrificing.
The professor caught my attention because he was so unlike Ben Stokes. Whereas Ben was cowed by Angelique, Elliot stood up to her. Prof. Stokes was bold and haughty. He knew all there was to know about the supernatural and his assistance was invaluable. I admired Thayer for being able to switch gears so swiftly and effectively. And, I always got a kick out of the professor's occasional sarcasm and his constant, intelligent dialogue.
Petofi was essentially an evil version of Stokes; he was also intelligent, cultured, and skilled in Occult practices, but he used his powers selfishly, to commit evil acts rather than to help. This character began to annoy me with his seeming invincibility as 1897 dragged on, but it was fun to watch him plotting.
ProfStokes