How is Poe Han? Poe was supposed to be killed off in this movie in the original draft. Poe is wedge. Finn is essentially a gun slinger comic relief character like Han
Han was always sure of himself and in control. He oozed confidence. Didn't give a damn about shooting first and had a sketchy past. That extra layer added to him.
I think they limited Fin by making him the "first storm trooper to not want kill anybody". Its too clean, its too neat. Make him battle tested and then change his mind adds more to him. Instead he was a guy who in his first battle just wanted to run (which is ok, but could have been more.)
So when he decided NOT to run and face Kylo Ren knowing that he's got no shot it means more for him and the audience.
Kylo, despite my thoughts on that final battle, has the most depth to him imo. It would have been cool seeing Kylo who is in the dark, but fights the light. Then we have Fin who has practically been brought up in the *dark* so to speak, killing people etc, now deciding to embrace the light. Embrace doing the right things to make up for the wrong things he did.
Kylo killed Han to truly join the dark side.
Fin fighting Kylo could have been his moment to embrace the goodness/being a hero.
I'm not saying anything was BAD. Just could have been better imo.
All in all, if he is indeed Han. Great.
If he's not, but still a strong character. Great.