What are you supposed to build as Renekton?
My advice: sightstone, QSS, thornmail and boots of swiftness! Be the superward your team probably doesn't deserve but with a D-D-D-Double Dash.
Carries do more damage than him and either have much more range or they can cover much more distance by meeting many fewer requirements. Assassins do more damage than him and can escape from threats, and aside from his Dominus they are just as tanky. Other melees have more utility than him while needing fewer tank items in order to stand taking hits. They can even choose to do just as much damage as Renekton can by building a Triforce or Sunfire Cape.
TL;DR: How's that rework coming along, Riot?
as first item. Personal preference, but a lot of people like the 
for the auto-attack animation cancel
