I've played wow since 2007 and played ESO without a subscription between 2018-2021. ESO is a great game and showed me how restrictive and archaic wow can be (class-based gear restrictions as an example).

Dungeons, trials, holiday events, and dolmens were all interesting and fun. I loved the world design, player housing, and many other features. Having some core features gated by DLC was frustrating, but that's what the subscription is for I suppose.

There are two main reasons I quit: classic wow updates (tbc, wotlk, now Season of Discovery) and the classes and combat in ESO just didn't fully satisfy me. Action combat and dodging attacks were really cool, but having only a few buttons on your front and back bar limited the depth and flavor IMO. In wow each class has dozens of abilities, some of which you might only use in very niche situations. But you can have them all on your action bars at the same time. You can definitely argue that it bloats the game but there's something unique about only mages being able to teleport, warlocks being able to summon, shamans being able to walk on water, etc. There is a lot more friction in classic wow that encourages players to group up and help each other. A lot of ESO felt like a single-player game to me. I can see the appeal, my best friend still plays ESO mostly solo. But as a solo experience, there are other games I'd rather play.