Chabot still for me. Fox is having an amazing year though. But Chabot has a better track record. I could change my view if Fox continues to play at this level next year.
Track record? Fox's 107 game track record is better than anything we've ever seen from Chabot. By a nontrivial margin.
It goes without saying that Fox is so much better defensively that it's not even worth discussing, so I assume Chabot's track record your referencing is based on offensive production?
Since Fox entered the league, he's posted 13g 78p in 107 games, good for 6th among all defenseman. Over that same span, Chabot has scored 10g 63p in 108 games.
Keep in mind Fox was a rookie for the majority of those games, and was getting limited ice time for like the first half of the season. Chabot played >500 minutes more ice time since Fox's debut and was still outproduced handedly.
Since the end of December 2019 (as he started getting more ice time and PP opportunities), Fox has 61p in 68gp. That puts him first among all defenseman (carlson is next with 57 points). Chabot had 39 points in that span, and his career high is 55 points in 70 games.
NHL Stats
When has Chabot ever done anything like that? Never, because he can't create offense like Fox.
Combined with Fox's aforementioned defensive superiority, and this is not even remotely close.