This list doesn't include champions in need of a full scale update. Just the ones who could use better looking splash art (for certain skins), models, or both...
Art:
Models:
Both:
Cries in Leona
Seriously how do you forget 
she has one of the least dynamic outdated splasharts
are already on the list for skin splash updates
They need both too :
are going to get full VGU one day, Rammus is among top 9 candidate for a VGU, so he is definitely sooner than later.
Its already in there but i feel like Zilean really needs it hard started playing him lately and damm his model looks outdated.
Nearly every champion on your lists needs full VGUs (of major or minor degrees) with exception to Graves, Sivir, Nasus, Talon, Annie, Alistar, and Ziggs.
Sivir, Nasus, Graves, Annie, and Talon need new splashes. Ziggs is mostly fine as is. Alistar needs new splashes, a new VO, and new animations, because his model and his kit have been modernized.
Disagree on Annie, Alistar and Ziggs for updates models. I'm not sure about xin zhao though
