Defensive metrics question
I am still in the beginning stages of learning stat analysis, and I find that there are several different metrics for defense. I am currently checking UZR at FanGraphs, because it's a free site and UZR seems to be a respected stat. However, there is the Baseball Prospectus site (I don't know what statistic it uses for defense), as well as Bill James' site with Runs Saved.
So, my question is this: Is UZR the best single statistic to use to measure defense, or would it be worth the money to learn what is being offered on one of those other sites?
Born to an age where horror has become commonplace, where tragedy has, by its monotonous repetition, become a parody of sorrow, we need to fence off a few parks where humans try to be fair, where skill has some hope of reward, [and] where absurdity has a harder time than usual getting a ticket." -- Thomas Boswell, 1984