I make my own mostly because I enjoy making my own food. But it's also a lot cheaper and a bit easier on the environment. A 32 oz glass jar of White Mountain yogurt is almost $10 whereas a gallon of Whole Foods milk is $7.00. So $7 vs $40, and four fewer glass jars each batch.
Since I start by cloning White Mountain, my yogurt is basically identical and the taste is the same.