Statistically
Championships
Scottie has 6, Kawhi has 2. It could be argued that Scottie’s role in all 6 was much more significant than Kawhi’s first (only averaged 12 a game but he also guarded LeBron). On the other hand, Kawhi’s role in his second was greater than any of Scottie’s. So Scottie gets the edge but it’s noteworthy that he failed to get there without Michael.
Eye-test
Scottie was a better passer, but everything else he did Kawhi seems to be doing better. Scottie’s distinctive qualities are his defensive prowess, length, and offensive consistency. Kawhi does this better. Scottie was a winner, Kawhi has proven the same. They are both good teammates, reliable in clutch situations, and don’t have a notable flaw.
So who is better? The answer is influenced by what you’re trying to do. If you’re ranking careers you have to pick Scottie Pippen. He played 8 more seasons, won 4 more rings, with nearly identical stats and one significant advantage. But if you’re comparing who is individually better and who I’d predict will end up with a better career, it’s Kawhi Leonard