I own both Eagle Creek and Lewis and Clarke brand of compression bags, and these Gonex are very comparable if you are more price conscientious without wanting to sacrifice TOO much for quality/function. My Lewis and Clarke brand ones are almost identical in design, so honestly, I couldn't tell the difference. Except, my Lewis and Clarke bags don't have the nifty pull handles!
I was able to put 3 cotton shirts and 2 pairs Bermuda shorts in the Small size. The XS size I had 2 high impact sport bras, 1 workout spandex shorts, and 4 microfiber undies. I stuff my socks in my packed shoes, so I didn't add them in. I wear a size 12/Large in most clothing, so it's not like I have tiny clothes (although, to be fair, these are summer clothing). The long one is great for any additional stuff, including pants (because when those are rolled up, they tend to be the longest rolled pieces) and a pajama pant set (which is what I have). I packed for 6 days in these in a 19" X 15 square pack and had room for clunky boots, my toiletry/makeup bags and other knick knacks. I could have stuffed them a bit more full, but the down side to these great little compression bags, is that once they are stuffed, they make your backpack a lot heavier, reeeeeal quick. So, I played it safe and didn't overstuff. Would buy these again!