Both look great, IMO.
AS for them being replacements for other characters, how do people figure that?
I'm pretty sure when NRS decided the roster, they didn't say "These 2 characters will replace those 2 characters."
No, the likely scenario is that they sat down and said "Theses characters will work with the story that we plan to tell, and their gameplay goes well with the system we have."
I'm pretty sure that they didn't kick out ___________ favorite fan character for _____________ character.
Im no Jax fan, and I agree completely. I thought both looked great.