I did get the American Tourister ones that don't require a vacuum - just pack, seal & roll out the air.
As far as the Ziploc ones - I bought the 2.5 gallon ones - the zippers break after one or two zips. I also have the XL & the XXL ones, but they are just WAY too big.
I think I'll use them for the things that don't wrinkle easy, yet take up bigger space (sweatshirts, jammies etc) Then I'll pack my nice clothes on top. I just need a tiny bit more space, so not everything needs to be condensed - just big stuff.