Re: Onesies/One Pieces vs. T Shirts for EC?
I personally don't like onesies for EC'ing (even unsnapped), I think primarily because I have boys. My EC'ing friend uses them unsnapped all the time with her girls and has no trouble. I think gender makes a big difference. I chop off onesies all the time and never hem them, but I prefer actual shirts.
I second what was said above: newborns pee all the time and you'll be offering the potty so frequently, you'll need quick access. My favorite at home is a prefold with a prefold belt.