I'm basically in the same boat as O_O and GRCubsFan: I pretty much just use the newer statistics. However, my knowledge of how the trickier ones are calculated and used is sketchy in many cases (VORP, WARP, WARP3, etc.). For batters, I like a standard AVG/OBP/SLG line - I think OPS is overly used, and an inaccurate representation of a players' worth, as SLG is overrepresented in the overall stat (although OPS+ is very useful). I tend not to use statistics that I'm not sure of how they work, like EqA, VORP, WARP, WARP3, and so on, but when someone else uses them, I generally trust that they know what they're talking about - I just don't make use of them in my arguments. For pitchers, I like all these (which have been mentioned before): ERA (sort of), ERA+, WHIP (sort of), H/9, BB/9, K/9, HR/9, K/BB, GB%, FB%, LD%. However, I'm also a big fan of OBP against and SLG against - I figure if they're good enough for batters, then they're good enough for pitchers. SLG against is particularly useful, because outside of HR/9, there's really no other stat that deals with how many XBH's a pitcher gives up, and that's pretty important.