JJ and Kleiza are pretty close offensively with a bit of an edge to Kleiza's range and FT shooting. Kleiza has also played over twice as many games and this year we never saw an upswing in his game like we did with JJ. Defensively it's a mismatch in JJ's favor.
I'd start JJ and be happy with it unless they need more than 10-12 pts from the three.