The best counter to top lane Hecarim is...
...AD bruiser 
.
Seriously I hope that nobody discovers that AD Fizz is still viable and good. He admittedly isn't as good as before, but he is still good. And he is my go-to pick against 
everytime I go against him.
All I have to do is play safe early, as Hecarim is actually stronger at this phase of game. With the Seastone Trident changes, it is very easy to last hit, and starting with 
+ 3 
means that Hecarim will not be able to easily harass Fizz out of lane. You can even start with 
+ 5 pots to lower the damage from Rampage, but this means that you have to conserve mana.
Rush a 
. If you are able to do that and you have Chum the Waters, then Hecarim will have difficulty to 1x1 Fizz, even if he is using 
. You can even all-in him pretty safely. Once you have 
Hecarim will never be able to 1x1 him.
Fizz has enough mobility to be able to properly deal with Hecarim during fights, and the slow from Chum the Waters will cripple him a lot, especially if Hecarim is trying to go against a squishy target on your team.
After BotRK I suggest to start building tanky, you have to be tanky when the mid game comes, although you can buy 
earlier if you are snowballing. I actually like to buy 
against Hecarim, I can use the slow to stick to him during fights, and to peel him out of my ADC.
I really don't think that Hecarim is that strong, and I hope that this will help people.
