A lot of the real authentic BBQ from years past has left St. Louis. On the north side of town there are still a couple of holes in the wall that are decent. There's a joint called Grandpa Mischeaux's that specializes in gigantic burgers and half-way decent ribs. Ropers BBQ is also pretty tasty. My favorite joint in St. Louis was McCrary's, but somehow I don't think his real recipe was passed on to his relatives. Bandanan's was pretty good (depending on the day). I never was a big fan of Super Smokers. Believe it or not, it was the citrus flavor that turned me off. God, I hope those claims are not true.
I would have to say IMHO that the best BBQ in the St. Louis area would have to be Smoky Bones in Illinois. Really good smoke flavor, flavorful meat and the sauce was quite good.
Of course, I've lived in Maryland for the past four years so I'm sure things have changed.