These two champions are some of my favourite champs in the game. They have fun mechanics, plenty of counterplay, and are generally just in a very healthy state. But, on the matter of fanbase building, neither have really gotten any attention. When I'm talking about fanbase building I'm talking about things that draw attention to the champ; a good skin, a cinematic, anything that draws people to the champ.
I think Ori and Zilean are two champs with some of the most potential to become fan favourites, and still be healthy champs (unlike Irelia, Akali, Yasuo and Zed). Their themes and stories are good (if anyone hasn't read Ori's lore yet, go do it please) and their gameplay is fine. the problem is that it doesn't feel flashy, but this is mainly due to outdated visuals. Getting a 5-man stun with Zilean bombs or Ori ult is always amazing, but it just looks a bit meh. Zilean just nodded at you twice, and Ori's Ball just drew a circle around itself. That's why I think a VGU like Ezreal or Morgana got would suit them very well.
Now, I know there's plenty of champs out there that also don't get much fanbase building, but most less promoted champs are unhealthy in a way. Most need to snowball in order to be effective because they hold little tools to be effective if they don't have items (champs like Olaf for example), or they have some targetted CC that takes up 90% of their powerbudget. Ori and Zilean aren't like that. They both hold tools that stay relevant even when not doing well, but the tools are counterplayable, and when they get fed it's not impossible to win from them.
I think Ori and Zilean really deserve to get some more attention. Their animations are outdated, but their kits are still super relevant to this day. Please get their visuals up to date so more people will remember they exist.