I recently ordered a Wonder Wrap diaper cover. I was so impressed I had to tell you about it. I was eager to try one because it's a one-size cover - it has several rows of snaps so it will adjust to fit almost any size baby. It claims to fit from 9 to 35 pounds. As I mentioned, I have only just now tried one so I can't tell you how it fits a little baby. Jesse is around 20 pounds and he's got two larger settings to go. Being adjustable, it can easily save you money because one cover can replace about three (small, medium, and large).
Another feature that sets it apart from other covers is it doesn't have fold-over elastic around the waist. The elastic is a little lower in the waist (if that makes sense) and looks more comfortable. To try to show you what I mean, compare these two pictures.
Jesse's wearing a Bummis Super Whisper Wrap in this picture. The white trim you see around the legs and waist is fold-over elastic.
Here's Jesse in a Wonder Wrap. Wonder Wraps are available in several great colors. (This is Blackberry.) It's a little difficult to tell from the picture, but you may notice the bit of "flare" around his waist. The elastic is sandwiched in the cover about an inch from the seam.
There are two things about the Wonder Wrap that some might consider disadvantages. It doesn't have the flap of PUL in the front under which you can tuck a trifolded prefold. You can still lay the prefold in it. If you snappi or pin then you probably don't care anyway. The Wonder Wrap also doesn't have gussets. I have covers with and without gussets, and I like both kinds. I don't find the lack of gussets to be a problem. I haven't done a side-by-side comparison (and Jesse's asleep in his Wonder Wrap at the moment) but the Wonder Wrap seems to be cut a little more generously through the crotch than the Bummis Super Whisper Wrap. So even if you're a die-hard gusset fan, you might still want to try one. I think I've got to get a couple more!