First off sorry if you don't have one of these bookstores in your area/country.
I am constantly in a struggle with these two stores. I love Books-a-Million, but it is farther for me to reach than my local Barnes and Noble. I always choose to drive the extra twenty minutes to go to BAM for several reasons: 1. Their discount section is enormous and consists of every category in the store. 2. The staff is always much friendlier and always willing to help. 3. The atmosphere is much more relaxed and I don't feel like I am being judged by everyone who passes through the aisle I am on.
If you feel the same or even if your opinion differs let me know what you think and share your stories.