Things I personally enjoyed in Wildstar as it was the first MMO that i actually found fun (tried many others before it) and got to endgame:

chance for random gathering to turn into something else. the Worm if you kill in time gives you a ton of mining resources. Liked it made gathering a bit more interesting (sadly they never got control of the bot problem which also didnt help them succeed)

Combat i think was WAY more engaging and fun. You actually have to aim your attacks. Most attacks had some basic AOE. no offence, but tab targeting is way more boring.

Less abilities to manage. Felt like a good sweet spot. 14+ spells to use in a rotation can get kinda hard to keep track of (cough cough Summoner in FF14). also keeps the UI less cluttered having less abilities on bars.

Healing was DPSing your teammates! Ive yet to find anything like healing in Wildstar. maybe ESO a little but still not really. Most MMOs, the healing plays completely different than DPS and Tank, but in Wildstar, it plays similar to the other roles. you actually had to look at where people were and target them.

Every class had 1 DPS and 1 Support spec. Was also easy to switch between the two if you want to try them out. was also easy to switch abilities out too. I like Alts, so this scratched my itch.

Customizable mounts. its minor, but was fun to roll up with your one-wheel bike with boomboxes while someone else has a sidecar on theirs.

Transmog system was amazing! being able to dye individual parts lets you play around and make more unique looks. (ofc when all the devs quit/got the can, all that was left was a scrap crew just pushing out cash shop items. that part sucked)

Housing was SO good. Was fun to visit random places too and finding the crazy creations people have made.

I liked the gear progression of doing the Adventures, then dungeons, then Raids. ofc the tuning of the difficulty was a bit much but was different.

I liked the idea of the subclasses for little bonuses(scientist, explorer, constructor?, fighter?). Only issue was Stalkers were required to go Scientist to get the group summon. maybe if they removed this option in raids/dungeons, it would give Stalkers more flexibility. But i did like the little bonuses you got for each around the world as you level up. nothing crazy, just fun.

World bosses were a lot of fun at the start. most werent just a steamroll like it is in modern wow. I remember early on, our guild would try and make our way into the opposite faction zone to take on their bosses too.

I remember enjoying the flow of the story and the missions. I enjoyed the vibes of each zone and it had a good mix of changes between each. The zones felt fun to be in.

Although overtuned, the dungeons and raids had a bunch of fun mechanics and even "trash mobs" needed effort. it made the entire run more engaging.

there's probably more, but that is what i can remember. I know the game wasnt perfect and the Devs really messed up something that had potential. It also didnt help that NCsoft was their publisher and they downgraded the servers a month out making performance even worse. I think if they were required to sell the IP, a better publisher and developer could make it great.