As a reader, I relate to Proctor more than to any of the other characters. This is the design of the play, I think.
Proctor is flawed, like all of us are, but he is striving to find his strength and his goodness, despite self-doubt. His higher impulses are instinctual and primary to his character and lead him to his (qualified) redemption in the end.
I can relate to him. I am suspicious of organized religion. I try to be a good person, but like all humans, am not perfect. I wonder what I would have done in his situation, or if I would have had the courage in the end to die for my name rather than confess to let the Church save face, especially if it meant I might survive. I don't know that I am that strong, but I like to think so.
I would not call him evil; I would simply call him human. He gave into a temptation just like we all do. We might not give in to that particular temptation but we all give into something. Because of that I can definitely relate to him. In the beginning, he wants so badly to make things right with Elizabeth, but he wants it to happen quickly without rebuilding her trust. He struggles more with forgiving himself than receiving the forgiveness of others for what he's done. He passionately loves his family and does everything he can for them. I think Miller portrayed him as a powerful, passionate and very human.
Yes, he makes a mistake, but in the end does the right thing. I think in the big scheme of things, that is what counts. He gave in to temptation at a weak time in his life and that sin eventually led to the accusations in the play.
I think Proctor is admirable. He is a little arrogant in the beginning when he confronts Parris and Putnam and sometimes goes about things the wrong way, but in the end he sticks to his beliefs, he doesn't lie, and he dies for it. He loves his wife, he loves his children, and he's truly sorry for his lapse in morality.
I can relate to Proctor on some level. He has a deep intolerance for the hypocrisy of authority figures, i.e. Parris, and it is certainly understandable. True-Proctor lacks finesse in asserting his discontent, but he tries to stand by his convictions and does not go out of his way to cause others distress. He is not well versed in social politics-something many people suffer from.
He also gave in to temptation, but that does not make him evil in my eyes, just weak. In the aftermath, Proctor tries to be careful of Elizabeth's feelings, and when she is accused he shows how much respect he has for her.