Every now and then you can get bad air. Sometimes it's not the compressor but instead the tank that's bad. I always recommend smelling the air before you leave the shop just to be sure. Just like sour milk or a skunk beer, you can end up with it even from the most reputable and reliable source. Take a whiff when you pick up the tanks and you will prevent most problems with diving on contaminated air.
B&B has great air, as do all the shops here. You will probably only save pennies between shops so is it really worth it to worry too much about where to get the "best" air deal?? I would place convenience at the top of my priority list when it comes to this subject. Who will be closest and most readily accessible to you?
I will say, in over nine years, I've never had a bad (or low) fill from B&B SCUBA at Azeka Place!