Shawn Marion for Emeka Okafor?

Who get's the better deal? It's for my NBA Fantasy. I want to keep Marion, but I'm worried he won't be consistent this year. But then, I don't want to trade him because what if he ends up turning around his season and exploded with his numbers. Emeka Okafor is obviously not an explosive scorer, but always gets you rebounds and blocks. What should I do?