In a tier list:
A Tier:

B Tier:

C Tier:

A tier picks are in need of a LOT of help and generally don't do very well when put into a specific area of play.
Rammus jg is weak because of slow clears.
Poor Morde just wants some love after all these years of being shoved from botlane to toplane to midlane.
Irelia is doing poorly against most juggernauts at the moment, I can't confirm if the Sterak's buff and the Gargoyle's plate buff helped her. I will test this more later.
Nunu is debatable on whether he really NEEDS a VGU but considering how Yorick, Taric, and Warwick came out... I am willing to bet that he'd benefit from one.
Skarner's been pushed back in a fashion to old Yorick and as such he deserves to have a VGU after urgot and eve.
B tier picks were champs that do a job and can be fun to play but they need some love to be more fun to play to a larger audience/fill a healthier role than "point and click adventure"
It can be fun as Soraka at times to save all your allies from a bad towerdive that they otherwise would have killed themselves during but lategame she becomes a healbot with almost no purposeful thought able to happen properly.
Pantheon is a giant point-and-click adventure.
Xin has bootleg Pantheon problems.
Tryn has bootleg Xin problems.
C Tier: these guys could use some love from a VGU. They still are fun to play for a good portion of people, however.