Definitely Gwen! Clearly because he is human and capable of empathizing and feeling just like Na-in (who was also human before he died, and Amon ate and rebirthed as an immortal.) But that is not to say that I hate Amon. Disliking him for being a predatory dragon that cannot relate to other humans is unfair. He cannot help what he was born as. Affection for Na-in is probably the only thing he can feel. Outside of that, he feels nothing beyond the predatory instincts of his reptilian dragon brain.
If anything, I feel sorry for Amon. He deserves a partner too preferably one of his own kin. His relationship with Na-in seems doomed- as one or both of them will always feel out of place in that relationship, as well as suffer with their emotional, mental, and spiritual needs not being met. Furthermore, Na-in is doing most of the sacrificing and compromising, especially through Amon's manipulation of his memory and life to hand-tailor Na-in to Amon's life and likes. Manipulation in relationships never works out.
I don't understand people making excuses for Amon, personally. I don't even hate him but I get tired of seeing people thinking "he doesn't understand" and "he doesn't have emotions" to excuse his behavior. I just don't care why, I don't like how he acts, regardless of the reason. I'm a poly lover though so I'm fine with ending up w both lol

Amon or Gwen, y'all? (Who do you like more)