TBS, and liverocks.com both have nearly sterling reps.
I believe that TBS rock tends to have more life on it, but that means slightly more die-off during transit, and more negative hitchhikers like mantis shimp. I've seen several peoples new tanks after they got a large shipment of TBS, and it had lots of sponges, some stars, feather worms, etc... They all had to spend a bit of time catching mantis shrimp out before they could start adding their own critters. But since you have to wait for a tank to cycle anyway, it's much more fun to look at and catching mantis shimp gives you something to do.
B