Hi there,
I think the value rooms are all very similar in size. Pop was the most recently built but the All Star Music and Sports have recently undergone rennovations - perhaps that's why someone said those rooms are better? Really I think it comes down to personal preference, mostly as to theme. All Star Music has some family suites, we stayed in one last December and enjoyed it very much. Also all the All-Stars are very close to each other, if you wanted to check the others out, and in the Animal Kingdom resort area, with a McDonalds down the street (sometimes nice if you have a car). Not sure exactly what you are looking for, or what is important to you? A few more details on that might help as far as getting opinions on which would be better for you.
Have a good day.