Im sorry you had a negative experience at UnderWater Connection. Everyone has off days, and hopefully your experience was not typical. Still, assuming you interfaced with the retail staff, you might or might not have been interfacing with an instructor. Since the instructor is the one who will really matter most during your kids training, you might want to consider giving UnderWater Connection another chance. Perhaps ask if you can schedule private lessons with one of their more kid-friendly instructors.
Of course that advice applies to any dive shop. The main benefit of UnderWater Connection is that they are local to you so you wont have as much driving for the sessions.
I honestly dont think there are large differences among the scuba shops available to you.
disclosure: Until I moved a couple of years ago, I worked at UnderWater Connection as one of several part-time instructors. I had chosen them from what were then three scuba shops in the Springs, because they had the most friendly attitude. The other two are now out of business. Sad, because neither of them were bad either.