I just got my Tab A 7" today and im loving it. Here's a video that helped me with this same choice
https://www.youtube.com/watch?v=Bp20_LYZ2Ps
they both have almost the same hardware but the Tab A has a much better screen.
So I checked if I was up to date on everything and i'm still having this problem. My tab connects fine to the pc as well as kies but kies does not recognize it as a samsung devise. Any ideas why?