I bought my started set up at Karp's and later realized I could have done much better at Arbor. Arbor seems to have a better selection of equipment and gadgets. Karps and Brew Brothers seems to carry the basics (equipment) for reasonable prices. I'm not all grain yet, and I have been buying mostly kits on line. Brew bros kits always seem to me like they've been sitting there awhile (but they may not have been). Arbor carries brewers best and those are dated. One thing that bothers me about arbor is that they don't carry wyeast. Brew bros does, but just a basic selection. That may be normal for local stores. For me, brew bros are 5 minuntes from the house and arbor is 5 minutes from work, so I'm very lucky. For basics I'll go to whichever I happen to be near when I have a few minutes. I don't think I'll be going to Karp's much anymore, but they may change when I switch to all grain.
One last comment: I find that talking to the brew bros guys is most helpful. Arbor people are helpful too, but the methods that they advise I think are a little more behind the times (think Charles's book, not John's). Karp's dude is good to talk to, but so often he's busy on the floor, and maybe a little too non-specific for beginners. He helped but didn't, when I was getting started, if that makes sense.