I don't like jungling, so I made this solo top build to see what people think.

Armor pen marks to help with Q and E.
Armor Seals/Magic Res. for helping you survive after iniating
Movement Speed Quints for his passive and chasing/escaping

21-1-8. This is a DPS build so I focused on his damage and utility movement speed for his passive.

Generally max Q first just for a better game. If you're getting your *** whooped max E for burst. Wriggles should also help so you don't really need to level out W unless you are having a hard time in terms of sustain.

Wriggles is good for just your sustain in general. If you know you are going to lane against a champion with heavy magic damage take boots and build merc treads and hexdrinker early. Would also again change skill sequence and max E so you still have damage (without sheen early your Q does not do much). Go for ninja tabi for the AD opponents. If you have a hybrid top, choose based on enemy team comp. or consider their CC. No matter what type of damage makes up the team, I think it is better to go merc treads if they are CC heavy. After wriggles and boots rush sheen. Next get phage since he doesn't need attack speed. At this point you can do whatever. Build Maw if you need MR, or Atmogs build for more defense and damage. You can always substitute Frozen Mallet if you need the extra slow/20 dmg.

Go for Exhaust and Ghost usually, or Heal is good too. Ghost for the passive and just helping his speed even more, Exhaust to close down on fast champs (Singed, etc.).

Damage
Aoe CC on ult
Initiator
Champ Design
Ability to jungle and solo top well
Hard to gank, ganking other lanes with Hecarim usually goes well
Fun to play.

Does not dominate every champ in top
A LOT of people play him

Hecarim's E gives you four seconds to charge in and knock back. Before starting the gank, pop E and run around since it gives you damage based on distance traveled. Especially with Sheen, this will give you a lot of burst by level thirteen combined with your Q damage. Remember he's fast too so most ganks should go well.

What I usually do is ping the target of focus. Then I start up my E and ult behind the target for the "fear" or whatever you want to call it, attack him (by this time your E is charged, knock back for your team and a good start in the fight). After knocking back, Q. You will basically spam your Q (low cd is why) for even more damage. The target should be killed fast, E should be up soon by the time you're almost done with the second target, if you pop it you have a good chance of taking the kill. Don't forget to pop W to stay alive in the fight. You should always use ghost since you get bonus AD during the fight, exhaust the carry, or if you have heal use it if someone on your team is about to die (If you win the fight your whole team can push or baron).

I'll start off by saying that you will win against ANY tank that lanes against you top lane. Should probably be careful with heavy carries like Fiora, she will burst you before you can do anything. Morde is OK, just make sure you poke him when the shield is down. Shutting him down early will win you the lane. Champs like Jax or Wukong will lose to you. Another champ that may be on even ends with you might be the average Yorick. Just remember you can run into the bush and the ghouls are gone. Remember he has mana problems early too, and he is extremely prone to ganks. Always remember to ward with wriggles, take advantage of where the enemy DOESN'T ward. Overall, try my build solo top and vote up if it works and comment why it didn't.