Lets be honest we got Demacia lore out the wazoo, but there are tons of places we know very little about when it comes to what they do in the world.
For me the place I would love to learn more about is The Shadow Isles. We have something like 10 champions from the Shadow Isles and they all have different backstories that hardly ever mention each other.
Zaun and Piltover.
Never getting enough from stories from there. There are fascinating places in these cities and I want to read about them.
Like the cultivairs in the depths of Zaun. The Ecliptic Vaults, which are supposed to be the safest bank in Runeterra. I want to read about a modern hospital in Piltover, finally showing us that healing on Runeterra is not limited to either magic or cutting off every ill limb and replacing it with metal.
I know, these cities are already served quite a bit with lore, but I am biased. Never enough lore from there. Also: The Zaun lore update didn't give us anything about Twitch and Singed, both champions related to chemtech, a subject we can still learn alot about in my opinion.
Piltover and Zaun. Last time it was touched it was on its rebuild in 2016...
Obviously First of all MORE IXTAL
Then more Bandle City because the last lore "update" for it was pretty sad. We learned almost nothing new about it and Riot promised they were going to deep dive on it or at least tell us more about the nature of Bandle City, Yordles and the magic that surrounds them. This didn't happen so we need more THIS YEAR.
Shurima, Modern Day Shurima. Azir taking back his Empire, Nasus finding his long lost brother, where Sivir and Taliyah are going next. WHERE THE F*** IS MY BOI RAMMUS All of this has been left hanging in favor of The Void, Icathia and The Darkin. People then go on to say that there is too much Shurima in the lore but really there is no Shurima, just the stuff that originated in Shurima gets a focus.
I really really want to see more Targon, learn not just about the celestials, but the Solari, Rakkor and Lunari and stories of everyday religious shenanigans. Proselytizing, Retributive Pogroms and Crazy all-out Fanatism. I want it to get WH40k up in here. For the God Emperor, Praise the Sun, By Azura By Azura By Azura levels of religious devotion. I actually want this above all things, but because Pantheon is coming next we know Targon lore is coming so there is no need to push on it. Hopefully we can shed more light on Celestial Aspects themselves if Pantheon remains Paantheon. If he becomes Atreus maybe less so, but a quest for him too align the Solari, Lunari and Rakkor against the space parasite menace in the sky (or A Sol, the mans been stuck in transit for like 4 years now) would be dope. Yes pls.
(Anything but Demacia right now it's getting a bit too much love)
I agree that P/Z is in for it's second round of updates, but I'd like to see some of the central Valoran buffer-states between Noxus and Demacia. The envoy from the Arbormark seemed like a chill guy, maybe we'll find out more?
######Also, more Tamara.
Some story progression in modern day with.... well I guess everyone already knows what I'm gonna say but I'll say it anyways.
S H U R I M A
We've been on a clifdhanger for 3-4 years already not to mention that current day Shurima has one of the most underdeveloped Regional page galleries and not even a dev diary official YT video like almost all other factions have
We need some more interaction between Piltover/Zaun and Bilgewater. They're way too close for how little they show up together.
The ancient history of Ionia is something I would like to know more about, and the Ionian characters who lack a lot of lore should also be expanded upon.
Piltover and Zaun should also get significant lore updates, for the regions themselves and the champions within them. I also think a few of the champions would benefit from at least a VU.
Bandle City could also use some more lore, and a few of the Yordles could use at least a VU.
Literally anything that isn't demacia. Shadow isles preferably. Why make truck loads of comics for a country filled with magist Meatheads when you could be making content for the island filled with spooky fellas.
Regarding the Shadow Isles, a good majority of people are guessing that the new marksman coming after the Pantheon rework will be a Blessed Isles champion, so we'll get a good bunch of lore from there soon, hopefully. Which is good, since the last Shadow Isles champion was Kalista, released a few seasons ago, making them currently the longest region to go without a champion. Yorick and Maokai did have their reworks after that, but those are reworks, not new champions.
And yeah, I agree. Piltover and Zaun, big time. I wonder if Riot avoids them because 1. They're not as popular with the weebs and overseas as places like Ionia or even Demacia or 2. They're very historically-based and they're afraid of touching on some baggage (though they don't seem to be afraid of that with Piltover mining out Ixtal). Another region (or region portion) I would want to see more of, which might have the same reason for a lack of attention, is the actual society of Bilgewater. Most of the new lore we've got from them is either about the sailor legends and tall tales or about the Serpent Isles, which is a whole different culture. I wanna see the pirates and their trade with Piltover and Zaun and how the actual cities deal with things.
basicly every region cuz its to hard to pick one.
That spot between Demacia and Noxus. What are you?
DEMACIA.
No, but really, I think Bandle City is waaaaay overdue. Some of my favorite Champions are from there, and getting just a taste in "The Whispering Doodad" (great read by the way, highly recommend) makes me want way more. I'd love more Yordles on the roster as well, feels like its been a while.
Piltover and Zaun also haven't been touched since Camille's release, basically. We did get Ezreal, which I loved, but since Ezreal is an explorer, he's not exactly heavily involved in Piltovian politics unless it concerns his archaeology. There's some great plots going on that haven't moved at all. And its criminal that we haven't gotten a Vi/Cait buddy cop story AT ALL. Seriously, who doesn't like a shiny steampunk world with an awesomely gritty underbelly? There's a lot of Piltover/Zaun fans, so I feel like these stories would be popular.
Honestly, I'm really happy when ANY faction gets some story progression, so I wouldn't be too upset even if we revisited someplace with a lot of lore and story like Bilgewater or the Freljord. Heck, since Bilge's last story arc, feels like it hasn't gotten much lore either. And other places like Ionia get a ton of Champions and a ton of setup, but absolutely no progression; most progression they've gotten is that Syndra got to be a potential part of the plot again.
Zaun and piltover
I want to see weird science wars with our science boiz
could be a rad event too
throw in iconic locals like 
All of these champs could work in a fun 1v1 story even. Like just pick any two, you can see why they'd fight, and enjoy the whole aesthetic of it,
The new place and targon
Void, Zaun or Piltover
##Honestly the Void.
##Other than Void, perhaps more lore on Shadow Isles perhaps.
Since no timeline is mentioned, I would love to see the ruins of demacia.
Zaun and in addition to that Mundo doing Mundo things
Noxus, specifically the du coueteau house >:c 
Zaun is pretty unknown imo.
