I've said this in another thread this is a completely subjective statement that depends on your role, the champion you play, and what type of player you are.
will always hate say Yasuo is unfair to play against because his kit blocks almost, 80% of their dmg with one skill.
will also feel
is unfair to play against too, because they have to deal with the free harass that Kayle gets and can't do much about it because her kit is so pro-kit and a powerful range kit.
The same can be said with assassins vs adc's, assassin completely prey on immobile squishy targets that allows them to burst that target as fast as possible with little reaction. Adc's are will of course feel that it is unfair to play against because assassins prey on squishy targets and adc are the most squishy.
Also players who like to brawl and love 1v1 say top or mid, mostly top. A top player will hate skrimishers, because their design is based on a strong 1v1 ability, they will feel that its an unfair advantage.
I feel these are factors in what is unfair to play against, when we look at yasuo his kit is strong 1v1 especially late game, ppl will hate that because they will ignore the fact that he is a strong 1v1 champion fight him and say thats just unfair. They take their champions weakness and think that it must be the other champion that is unfair, the same with fizz, against most immoblie targets that have flash on cd, they feel that his ult is bs because if he hits it your dead. They seem to ignore the fact that fizz's burst is significantly hindered with out his ult because its not even save to go in without it.
Another example is zac, with champions like zac with so much cc, the mere fact that if you get hit by cc feels unfair because once hit by it you are stunned for a certain duration you cant do anything. Yet the fact that zac can miss all his skills, that zac's e is actually dodgeable and his q is dodgeable if he misses the first part and is out of range from you and a object to smash. R is flashable if he misses his e.
A champion like Yasuo or Fiora will be highly banned by top laners and I dont think it is unreasonable, because top is a heavy 1v1 lane and champions that are strong 1v1 will feel unfair to play against, but ppl need to understand that just like most champions are countered by other champions these champions can be countered too.
I kind of have a problem with 5 bans but its subjective. Bans seem to no longer have any stragetic value its just I dont want to play against this champion so I will ban him, I dont think it is unreasonable but it really doesn't give ppl a chance to learn how to properly play against a champion in a competitive setting. I dont think it has to do with the strength of a champion because the most banned champions dont even win that often r have the highest winrates, its those that ppl feel are unfair to play against.