In regards to fish health...
My PetSmart keeps their tanks really clean and the Bettas are look healthy. Petco I will agree, has more varity, but my Petco was absolutly horrible in regards to health and man they overstocked!( they were feeding big goldfish little feeder goldfish!(Isaw!) and there were dead fish floating around, ugh.
I will say this though, My Walmart was 1% better than petco, but they closed the livefish section down.
Hmm, well I have a lot of fish...