If I can just pip in here with my homerism, I will point out that he got a puncture after tapping Buemi, and subsequently lost 12s as you can see on the FIA Race Lap Analysis. Deducting that 12s from his overall race time would've have got him into 8th. Whether the tap was Kobayashi's or Buemi's fault, I haven't quite figured out, but needless to say, an even more impressive performance could've been on the cards.
Having said that though, Buemi's drive is still arguably better purely down to the speculation that it's probably not as quick a car as the Sauber over a race distance.