I think Tony is the best defender on Kobe, but Ray is the best SG for the Celtics, due to his floor spacing. Both Ray and Tony have been making Kobe work hard.
I will say, I've earned a bit of a new found respect for Kobe's game, though. Some of the shots he can make are disgustingly sick. I know, I'm a bit late to the party on that, but the Celts have such a tendency to take him out of his game that you rarely see that stuff. (I still hate Kobe the person and Kobe the teammate, though.)