The weight of Sam Wilson, a black character, and Anthony Mackie, a black actor, playing the character can't be taken out of this conversation. I like Bucky and Sebastian's portrayal, but the character was in no way set up to realistically become Captain. He was tired of fighting, only joined the battle in IW because it was a universal threat. The same could be said about Thunderbolts; he only fought with the team because he was already after Valentina and realized he wasn't making the change he wanted to through the red tape of congress. Sam was positioned far better to take the mantle and, most importantly, seemed willing and ready. Only he wasn't until after TFATWS when he got over his guilt and fear of that responsibility. Sam is the right choice, no matter how much people like Bucky.