To talk less about who's the most outdated champ now that Sion's been dealt with (IMO its
Nunu and the derp-yeti Willump) and instead about who's likely to get a VU next, what Ironstylus said in the Q&A holds true, too many huge VU projects and they'll end up driving themselves insane, and have an overall slower work flow. I mean, Sion's only the fourth champ this year with a full VU that redid everything. So what's next for them will likely be smaller scope.
Immediately this rules out guys with gameplay problems like
Urgot,
Shaco and
Poppy, who not only have outdated models and VO, but also inherent kit issues they'd want to address with the VU.
It also rules out folks like
Cho'Gath, who will likely have a TON of work to be done in terms of visuals to make them as amazing as possible (I mean Cho'Gath could have a growing, developing body and stuff. That would take a ton of time).
So the likely candidates for a lower scope VU would be guys who's theme is solid, the kits are fine, who's lore doesn't need much changed, but still absolutely need a VU. This can mean quite a few folks are possibly coming soon:
- Nunu

I think we can all agree, he needs some work. Willump thumps around like a derpy gorilla, and Nunu's barely visually acknowledgable as an actual part of him, despite being the brains behind the duo.
- Teemo

Love him or hate him, he's got sticks for legs and barely anything going on animation wise.
- Tristana

Those painted on eyes are gonna have to go at some point. Also she has Teemo legs.
- Ryze

One of League's most iconic characters still suffers from pizza feet. Lets also say, his magic is nothing like in his lore. What's he use in game? lightning. What does he use in the lore? Thorns magic. WHAT IS THIS I DON'T EVEN KNOW GAH!!!
- Jax

Another iconic champ, an all time favorite who's gonna need some lore attention now that the League's not a thing, there's so much they can do with Jax. They're gonna have to be careful with that turret whacking noise though, cuz people LOVE that noise.
- Fiddlesticks

He's strange to me because even though he's bare bones in a lot of ways, his thematic means he just about gets away with it. But on a VFX side, considering how different pre-vu and post-vu Karthus are, there's a tonne that can be done with Fiddle here.
- Singed

This one seems like an easy choice. So much potential here.
- Malphite

Let's make him BIG. He's the size of a mountain, so lets BIG HIM THE HELL UP.
- Blitzcrank

Again, like Singed, there's so much that can be done here.
- Veigar

Veigar will need a bit more love than most because he's more black-mage rip off and less Yordle. He needs more Yordleness too him. Yordleness is now a word. Deal with it.
The list goes on. I just described a few, and all of them are beta champs. There's still quite a few post-release champs that need some visual work, and are also pretty low scope. Kennen, Akali, Shen, Gragas, Ezreal, Pantheon, so many! But something to keep in mind for the next champion VU:
It's likely gonna be low scope, considering how high scope re-doing Sion was.