Can I say no when my step dad asked me if I loved him as much as my dad?
How do you feel about your dad in comparison?
My dad is the only thing I have left in this world, he is nothing compared to him.
It's good that you were honest with your stepfather about how you felt. However, you should also consider someone's feelings when you tell them something. Hurting someone emotionally will affect the bond that you both could have.
I see him as a man and he is not my step father but some random guy I have to put up with. I don't owe him anything
I totally get why you feel that way, but still, you don't want to burn your bridges. I think you can just be honest and tell him you don't want to be rude because dads should not be compared as it wouldn't be fair to do so. If your step-dad wants to do better, then he should show it with actions.