Nash, 38, is undoubtedly the better player at this stage of his career, but Kidd, 39, would help the Knicks in a different way.
The South African-born Nash would need to play starter's minutes to be effective for the Knicks. He's at his best when he is the one running the show at the center of the offense. The Knicks, as I'm sure you already know, cannot afford to have another player like that on the court.
Their main problem is that they don't have enough balls on the court to accommodate the scorers that they have.
Carmelo Anthony—despite his top-five offensive talent—is a ball-stopper extraordinaire. He needs the ball in his hands to be the offensive juggernaut that we have come to know.
Amar'e Stoudemire is more of the same. He needs to be in the pick-and-roll offense for most of the game to get his points. Nash would help him with the pick-and-roll, but it would take the ball out of Anthony's hands too often.
Kidd averaged 28.7 minutes per game last season. That number would certainly drop if he were to join the Knicks. In fact, he told ESPN that he would love to play the role of Jeremy Lin's mentor:
"That would be a lot of fun to help a player like that," he said. "Just share the things that helped me be successful in this league."
That's exactly what the Knicks need. They need an established All-Star point guard to come in and teach Lin the ins and outs of the point guard position.
Lin did plenty of scoring during his improbable run last season, but he didn't show the ability to be an effective floor general under Mike D'Antoni or Woodson. With Kidd on the roster and at practice, Lin would be molded into a formidable combo guard.
Not to mention Kidd would come at a cheaper price than Nash. His skills have deteriorated much faster than his former teammate, and he surely realizes that he isn't worth much more than a couple million.
Kidd has already become accustomed to taking a back seat to another star on the team. He played with Dirk Nowitzki for the last few seasons, and would have no problem defaulting to Anthony and Stoudemire.
Nash is much different. He is used to being the veteran leader on his team. Last year with the Phoenix Suns, he took a back seat to nobody. The team ran through him.
Obviously, Nash is a better player, but Kidd is better for the Knicks.