So I have gotten 2 so far, and both have been a slight disaster. First, I got a large baby-pants onesie, which was huge and sagged way too much. I ended up using it as a onesie when I put on a super thick, layered diaper, like a few disposables or a disposable with a couple cloths. I've since lost interest in that sort of thing... I like just a disposable or disposable + 1 cloth prefold when I'm feelin frisky.
Then, I went to AwwSoCute, cus they were having a sale. I got a medium, and it was way too small. It would work with a really thin diaper like a TSM, but still I couldn't sit down... Otherwise the snaps would pop open.
So I'm 0 for 2 on onesies at the moment. I'm thinking of going back to baby-pants and getting a medium, but idk which color/design to get.