I'm a sucker for dominant defensive players. Huge fan of KG's game here!
Guys like Kobe, KG, Karl Malone, Moses, Jerry West, Dirk, Barkley were all stunning players. Really difficult to rank them in terms of talent. It's way easier to rank them in terms of accomplishments. What breaks the tie for me is ring count. Kobe got 5, KG got 1. It's as simple as that.
Sure, he was playing second fiddle to Shaq. He wasn't the best player in the 2010 Finals. I get all of that. At the end of the day, it doesn't really matter. What matters is the fact that he won. It's not like he were a role player with multiple rings (Robert Horry). He was always among the protagonists (if not the main protagonist).
Luck plays a big role in success. KG got drafted by the Wolves. Kobe got drafted by the Hornets, but immediately got traded to the Lakers. I firmly believe that if KG were playing for the Lakers (or the Spurs under Pop) he would have had way more rings. Tough luck for KG, but it is what it is.