What brand was it? Yogurt was actually my main concern about going vegan since I ate one every day. I have tried pretty much every brand.
My favorite is Trader Joe's brand, and Silk is second.
Oh, and the So Delicious Coconut Milk yogurts are really good, but pretty expensive (about $2 each), so I usually don't buy it. They sure do taste good though!
I really didn't like any of the other brands... Whole Soy or Wildwood I think. O'Soy has dairy cultures in it, but I think I tried it before I knew that, and didn't like it.