I love playing Junglers
Sadly I can't buy most of them because it would weaken my ARAM champion pool.
My opinion of what is bad is based on my own experience as a 2000+ ARAM MMR player ( https://euw.whatismymmr.com/dr%20poro ) in addition to raw statistics from http://www.op.gg/statistics/champion/ using 'everyone' to see low ELO performance and Diamond or Platinum to show the influence of skill.
With bad junglers, I mean
(ironic how she used to be one of the top tier ARAM champs)
Then there are
who also have bad winrates but I actually enjoy playing them here.
I already own most of the champions, it's just that the 13 champs that I don't own yet all have low ARAM winrates and most of them are junglers.

much strank ;)
hue