+1 for many advices to choose an instructor, not the shop.
If I had to redo my certs, I would find a dive shop that looks respectable, find out their standards, and .... wait for someone who is a customer of theirs and ask them in the parking lot what they think. Here is why:
My OW cert was done during one of the vacations, great instructor, practical teaching (as in he knew how to show not just books)
For my AOW cert, I figured I will go local -- cold water, NJ, tougher environment to dive in and (I assumed) better teaching.
My AOW classes from learning perspective were a waste of money. Sure, I got the card and learned one important thing: an instructor could be a very good diver, but if he cant explain, gets confused in basic words (expansion / contraction), loses 5 of 7 students under water, ends up in a wrong spot .... he cant teach you much of anything but to think of how to chose a better instructor. Later on, I was at the same shop buying some hoses, someone in the parking lot asked me what I thought of their certification program, and I provided the honest answer ... yes, the shop didn't get the business, but the person asking most certainly got better education elsewhere.
When I was "interviewing" the shop before, everything checked out and I was told point blank, the instructor we were getting was one of the better ones. He was a good guy, and I liked him personally, but he was not a good teacher.
If you can afford to, go for a private class. It will be more expensive (probably not by much) but he/she will likely pay attention to YOU. Also, I have a nagging feeling female instructors will be better than males -- it is a hunch with no scientific evidence behind it, but every time I worked with a woman who taught, she seemed more competent and much more focused than her male counterparts.
Also an independent instructor does not want to sell you anything but his or her service whereas a shop will try to get you to buy their gear. I, personally, hate that. When my briefing for AOW cert dive was interrupted by the shop owner with "lets give the group a break so they can buy stuff" I realized what I was in for (when they sold a guy a $600 flashlight for a single night dive, I felt sick). Finally, when I was told that weights for the dive (in addition to rented dry suit and tanks) will be sold to me for $5 per pound and I can return them for $4 after the dive, I realized that was the last business transaction I would enter with them.
The point here is that dive shops are in the business of selling service and equipment and they will push until you get both. An independent dive instructor wants to sell a service and hope that a good word of mouth will bring in more business.