As far as pure cataloging service goes, I prefer Nook Exchange over Nookazon primarily because Nook Exchange has a simpler/cleaner interface, it's easier to access the features I need (example: do I have this item already? and how many items do I have available to trade that exists on someone else's wishlist?) and Nook Exchange is noticeably way faster in terms of item search speed.
Trying to use a substring of an item in the search bar at Nookazon on average takes seconds (I've seen it go for 10 seconds+ before; I ain't got time for that) versus milliseconds on Nook Exchange! However, I love the concept (at Nookazon) of listing trades and having a listing response system, but honestly, what I've experienced is: most people just use the Discord to list and trade (which due to the sheer size of the userbase is overwhelmingly chaotic and too fast-paced for my liking... this is why I like Belltree so much! I've had way more successes and accomplishments using Belltree than any other large AC trading community (i.e. Nookazon, Reddit, etc.).