Re: Pick up Brook Lopez or Manu Ginobili?
Well you already have plenty of big men, so Manu would be the best fit for your roster. I think he's more valuable either way though. His per-game averages were crazy before he got hurt.
And since you're in first place, you may want to consider picking up both Manu AND Lopez. You could probably get away with dropping D West (or Augustin since he's hurt and has been mediocre anyway). Manu and Lopez will be back in a month and they could really help you for the fantasy playoffs.