When I'm stuck between two games, I usually look at resale ability and value. In this case, I'd look at which game would be easier to sell if I end up not liking it. And to me the obvious answer here is JP. It has a larger market, and is a players game. If a reasonably priced JP came on the market around me, it would sell quickly. Whereas a reasonably priced Turtles would need a more specific buyer.
So the most logical thing to do would be to buy JP. If you end up not liking it, sell it and get a Turtles. If you go the other way, I think it will take you longer to sell Turtles, and you might need to lower the price to get it done, based on reputation of the game alone. JP for the win.