It may not seem like it, but there are many ways to build Renekton. He is very strong even after nerf as only his ult was weakened early game but it scales and is very strong mid and late game. Here is my build to top Renekton.
You want to focus on farm, and denying your opponents farm. The more farm the more gold = items. Renekton relies on his items a lot so its essential that you farm well. You should also be weary of ganks while pressuring, if you do get ganked you should be able to slice and dice out and flash if you have to. Dont forget to ward.
Playing his mid game is a bit tricky. If you get top tower early then you should roam mid and down to dragon to apply pressure and try to help in team fights. Try your best to make the most of it because you will be losing farm top.
If your farmed up and have almost full build or if you have full build then you will be able to properly bait fights and/or start them. You will be tanky enough to survive a bait.
Position yourself to Q nearly the whole team when your in ult. W the ADC or hyper carry to shut them down. Slice and dice through the whole team to maximize your damage.
Renekton is probably one of the best top laners in the game right now. I didn't so the lane match ups because I'm pretty lazy right now ^_^ sry but i will comment on some of them. You pretty much wreck all top laners. But, trundle, shyv, ryze are pretty hard matchups. Trundle is going to be a skill match up, ryze beats you hard so try to just farm under tower and avoid his Q, ASK FOR GANKS! hes pretty squishy early, shyvana is easy early but late game she beats you and just try to beat her early. Ok guys there's my build, this is my first build ever sorry if its a bit choppy. Please comment!!