(Not counting reworks)
Shurima - 
Freljord - 
(Unless we're getting technical, with 
originally being from there)
Noxus - 
The Void - either 
or 
Ionia - 
Bilgewater - 
Piltover - Soon to be 
Shadow Isles - 
(Again, not sure if they count since death is everywhere, but including them anyway. Before them it would be either 
or 
Zaun - 
Bandle City - 
Mt. Targon - 
Demacia - 
???
Did I miss any of them?
Gnar is from Freljord.
The most recent Bandle Yordle is Lulu 
.
But she was outcast from Bandle City, so you could argue it's actually Ziggs 
.
I guess you could also do the independent category which is basically like just skarner
Kindred is not from the Shadow Isle, they're not a part of any of the major factions/regions. They're an entity that exist throughout Runeterra.
Kindred isn't from the shadow isles(they are independent),so Kalista would be their most recent champion. And yeah Gnar isn't from bandle city either,he seemingly comes from the freljord and lives now in the same jungle as Rengar.(since Lulu is counted as a bandle champ on the universe site I'd say she would be the last bandle champ)
Rek'sai is listed as a void champ on the universe site so I would count her as one.
The most recent champion from demacia is actually 
And if you include "independent" as a faction,then the most recent champ of that would be Ivern(again going by the universe-categorization)
So if we sort the nations by how long they went without a new champion it would be: 1.Bandle City 2.Demacia 3.Freljord(not counting Ivern) 4.Shadow isles 5.Void 6.Zaun 7.Bilgewater 8.Ionia 9.Targon 10.Shurima 11.Noxus 12.Independent 13.Piltover(if we didn't count camille,then Piltover would be number 2)
