https://www.youtube.com/watch?v=xpwShY1YbDI
I personally always loved the "Treasure-Seeker" Quests. Make a Quest-Chain which can get RRREALLY tedious at Times. And then at the End of it, get rewarded with a really cool Item.
In the more "modern Settings", it could even be a really cool, rare Cosmetic or so. Or maybe a very badass Mount Skin.
The only Time i played such Quest-Chains in an MMO, was back in WoW. Sometimes even in the recent Expansions they manage such cool Treasure-Seeker Quest-Chains. These are the ones i like the most.
One more Game which has this - which is not an MMO -> is the of Course Sandbox Game of Sea of Thieves. Especially of Course the Tall Tales can shine with this kind of Tasks. Even if some of them are annoying as hell as the same time.
( Even good ol' Monkey Island Pixel PC Games had a few very cool ones. Good times, back then. Good times. )
Personally i think, as a Developer you can not do much wrong with Treasure-seeking Quest-Chains. You can create awesome, adventurous Experiences - which you can remember with Fun and Amusement even above 20 Years later.
Just a few Days ago -> i rode my Horse from the Sweat and Brow Quest-Chain along the Southern Coast down from Aela, all the way down along "southern" from the Desert - until the World-End/Border Wall ended my ride.
I realised there is such an enormous Amount of Coastline -> You could fill that for Example with differently huge or small Amount of Fisher-Tents or maybe small Fisher-Villages - which are not Nodes.
You could make Quests in which Adventurers ward off and defend these Places from Ocean Monster Attacks. And of Course -> You could insert Treasure-Seeking Questlines there.
Maybe a few SHIP-GRAVEYARD or Shipwreck-Quests or Quest-Chains there. When Sea of Thieves can do it, other Games can do it as well. Send the Adventurers there searching for Stuff that the Coastline-People lost : or hope it would arrive, but the Ships which were supposed to bring the Wares and Items in Question there, sank like a few Hundred Meters before they could bring in their Cargo.
The Potential is sure there. It just needs to get realised - and be it i don't know like Five or Ten Years in the Future if it must.