Which champion without canon lore do you want to see a new story of the most?
While Riot has been making great strides to bring every champion into the new lore of League of Legends, they still have a long way to go. It is true that every champion did get a paragraph or two a few months back as Riot finally got rid of the summoners once and for all, and while these tidbits are interesting, they are teasers for the full lore at best and placeholders at worst. Usually Riot updates champion lore when a new champion or rework of their faction comes out, but wild cards like Varus have happened a few times over the years.
With all that being said here are my personal 3 picks:
Vel'Koz - The new Void lore today was more of a Void teaser than anything else. It was awesome and I loved basically all of it aside from a few questions here and there, but we haven't actually seen the Void proper yet, just the effects the Void has on Runeterra itself. Being the brain of the Void and what seems to be the servant of some godlike entity (whatever Aurelion fears), Vel'Koz definitely understands not only the ins and outs of the Void itself, but the goal the Void and the gods who created it are trying to achieve. I'm hyped for that Lovecraftian entity, Riot.
Nautilus - Nautilus is an interesting champion because he made a guest appearance in the Shadow and Fortune story alongside Illaoi, and his couple of paragraphs paint him as an evil and vengeful demigod type creature who sinks ships in the ocean and offers the corpses to a god, probably Nagakabouros. Deep sea monsters have been teased forever by Riot and it's about time we get a monster in game, but Nautilus most certainly knows of these horrors of the deep, and seems to be one himself. I also think there's another side to Nautilus's story not on display in his little piece of lore, something either controlling him or him taking these dark actions to fend something else away. His mystery has me captivated.
Zilean - Zilean's lore has so much potential. My hope is that he'll get a VGU sooner rather than later, but he's not currently in the tier 1, so all I can hope for is some dank lore. He drifts through time and space in an attempt to save Icathia from destruction, and has become immortal along the way. There is so much trippy stuff Riot could do with a proper time travel story and Zilean has most certainly gleaned the nature of the Void and probably the whole of the universe in his travels, meaning he might be the most knowledgeable character outside of the gods like Bard, Aurelion, and Kindred. Can he undo the past? Probably not because all the other Void and Icathian champs would have their lores deleted. Can he change the course of time? I dunno what time travel method Riot subscribes to. If they ever do a proper Zilean overhaul, my body will be ready.

. Lux is already Sona's "biggest fan" and to discover that her idol is ALSO another mage secretly living in Demacia, well, to find a kindred spirit like that would be quite something, would it not?
Not a lot on him, his race, his home, ect. He only has his short bio, at an astounding 2 paragraphs long. No story, nothing.
. I think it'd be neat if she had some PTSD from her time in the war. Not that I think PTSD is neat or would wish it on anyone real, but I think it would make her more unique, interesting, and relatable.
He got left out in the Zaun lore update. I would enjoy reading more about his cruel experiments as well as the experiences he made on his way to find immortality. Maybe a story with him on battlefield, like that poison gas operation in Ionia he was involved in. Would fit to read about him striving the battlefield he bombed with his poison, investigating the corpses for some "data".
Where is his curse coming from? Did he break a taboo and this is his punishment? Was it an accident? Did he reject a girl who had a crush on Him?
I would like to know more and mummy stories are always entertaining.
More ties to Piltover, please. Let Piltover have an air force and he is part of it, while the people don't know they have a Yordle in a high military ranking in Piltover. Give us some details about Piltovian warfare, how is that city able to defend itself against the bigger nations?
With the departure of the IoW Nocturne doesn't really have a lore. I really want to see him and maybe Fiddlesticks get lore revamps to reintroduce them as living nightmares or something.
they kind of don't exist right now.
would be my personal pick if I could only have one. I want to know what the heck Bandle City is. Yordle lore is so messy, convuluted and somewhat contradictory at this point that it is begging for a full update. Yordles are one of League's most unique ideas and it deserves some serious love.
Her lore is pretty boring for me especially that I main her :/ it's really short and unsatisfying
and
(Kind of static right now in her position)
(Same as Lissandra)
Though his original lore might still work. (>_>)
: imprisoned within the depths of Noxus, driven insane, possible connection to the void depending on how far underground the Noxian dungeons go, no real timeframe of how long all this transpired. If he went as far back as
's reign, or if his imprisonment was under
's control. Need some answers, BUT NO SHORT ONES.