I actually really prefer to look at all three "slash stats" (AVG/OBP/SLG) because it helps provide context. I like to subtract the AVG from the OBP to see how patient a guy is, because just like not all .800 OPS's are equal, neither are all .380 OBP's. OPS is really a nice number, and I use it a bunch, but I think seeing all three seperate gives a truer, more complete picture of what kind of hitter a guy is - like if he's AVG dependent, for instance, or if he draws a bunch of walks, or hits a lot of homers and not much else, or a bunch of singles, etc.