I've been ordering from a bunch of different places lately. In the last month I've used Midwest, Northern, AHS, and Brewmaster's for the first time. I've used Rebel in the past. From my experience:
#1 AHS and Rebel - shipped really quickly, everything was perfect.
#2 Northern - Shipped a little slower than AHS, but only maybe a day or two longer. Order was perfect.
#3 Midwest - shipped out quickly, with 1 wrong item, but they were apologetic and sent out the correct item promptly, and told me to keep the mis-shipped item for free.
#4 Brewmasters - out-of-stock of half the order, they did send out the half they had in stock at no extra charge, and sent the rest of the order when they got it in stock. I ordered on Saturday, and didn't hear from them about the out-of-stock items until late Monday.
I just placed another order on Wednesday, and the order is still "pending" today on Sunday. I won't need the stuff for a week or so, but compared to every other vendor I've used it's not great. I'm not really sure I'll be using them in the future. I know they're the cheapest, but at this point I'd rather pay more and not worry about whether my stuff will arrive when I need it.