I state this with much weight on my heart. I feel as a biblical person I would be judas Iscariot. This may sound horrible to everyone that understands the gospel.
I believe that there are not different weights on sin. I believe that a sin is a sin regardless of what it is. Judas may have betrayed Jesus and sent him before trial that lead up to the crucifiction but I myself am also to blame for those events. If it were not for the sin in my life, Jesus Christ my Lord would not have had to lead the perfect life and surrender himself on the cross to pay for my sins. My betrayal may not be as directed as the betrayal of Judas but each time I sin and fall short of the glory of God it is only because of these events that I am able to be forgiven.
This is an extremely difficult question to answer. If I answer "Isaac", for example, then I am placing myself way above where I really am. If I say "Judas", then I am seriously denigrating myself. There aren't a lot of examples of people in the middle described in the Bible.
I would hope that I am heading towards being like Jesus Christ. On my journey to become like Him, I would also hope that I become like such people as Paul, John, Daniel, Isaac, and Abraham.