Gnar could use a very slight buff
His winrate for pro players (according to probuilds.net) is 47.19%. For the normal population (according to champion.gg) that has between 50-125 games is 48.68%. These are the group of people who have a lot of experience and should have a greater than a 50% winrate on him. Gnar is barely above Riven, yet Riot wants to buff Riven because she isn't seeing enough play. I don't know about you, but personally I would much rather deal with a Gnar than a Riven, even though both can be obnoxious at times. Overall, Gnar is a very well designed champion and does take skill to consistently pull off, while Riven at low levels does not require any skill. At higher levels, she does require a lot of mechanical skill and lane skill, but is not really as interesting to watch as Gnar, who can completely change the course of teamfights and has clearly defined periods of strength and weakness. If Riot is motivated by either what is fun to play against or what is going to get views, then Gnar is clearly a better option to have strong. Balance wise, he could use a buff, probably to something small like the base damage on Hyper or extra base resistances for Mega Gnar.
Furthermore, I would like to point out that Gnar counters the Juggernauts, and is one of the only champions that does so. Everybody would rather have Gnar than a Juggernaut like Darius or Illaoi, right?
To clarify, I know other champions could use work more than Gnar, and Gnar is not that weak, so I would like to see a very small buff to him. And I mean something like an extra 15 flat damage on Hyper.