In terms of design and abilities. Im thinking neon
I don't like how they took out the damage for the Neon wall. It made sense to take it out for teammates so your teammates dont take damage but enemies it made sense. Now all you see is people literally just swinging into the wall and killing the Neon which kinda almost makes her wall useless, I feel like if the damage was there for the enemy they wouldnt just swing into it, although i still like how it functions, you can literally split the side of a site in half but the fact that people just swing it now almost makes the wall look bad.
I think the over all kit of Phoenix was good initially but as the meta has changed and new agents have been added like KAYO he gets played ALOT less, plus with agents like Raze and Neon, even Jett, their abilities can add alot more in terms of team play where as Pheonix's kit feels really outdated. Good agent on paper its just hes really outdated, his "buff" still needs a work I feel.