I like Golden Spoon. There, I said it.
Golden Spoon was introduced to me by my wife (who is a big fan from California, where GS is well entrenched). I'm a fro-yo fan and frankly, there aren't a lot of good choices in Phoenix. Plus, I'm a bit of a traditionalist and don't like all the "Pinkberry-esque" places with green tea flavors and fresh fruit toppings. I want my yogurt served straight up, and I want a lot of choices of yogurt. Golden Spoon delivers in spades in this regard.
There are usually a dozen or so flavors to choose from. The sugar content is very reasonable, and if you want just a little bit they have a kiddie size that is about $2 - very reasonable. The portions are pretty big so don't order a larger size if you don't want it piled up.
One suggestion if you like to add toppings is to ask for a larger sized cup so that the toppings don't overflow out of the cup.
My favorite flavors are Peanut Butter Cup and Heath Bar - they go great together side-by-side