League of Legends (LoL) Question: Counter

Are you looking for champion picks? Personally I'd play Akali, Malphite or Kayle into Fiora, but there are more options than that. You could try Pantheon as he's pretty straightforward, plus his passive completely procs her vital procs.

Fiora is a powerful champion that has insane sustain and can easily make a quadra if not a penta kill in a team fight even if the one playing her is unskilled. Her mechanics are not that difficult especially if you are running her with a hydra since it can easily help you hit all vitals. Best way to counter her is with champions that can pressure her in lane, for example Pantheon, Renekton and Darius are such examples. I would personally recommend running jax against her, he is one of the few champions that can trade with her safely. Another way to beat her is through ganks, for example if your jungler is playing warwick and ults her and you are playing pantheon with the double stuns one after another even a Fiora should go down.

I personally prefer to ban her, but the way to counter her is to avoid the vitals, if you have "bad" one go back until you will lost it and then if you comes back you will get the one on the other side. in addition don't try to stun her until she use her W, try to find when she vulnerable and then engage, and wait for jungle pressure.