One of my absolute favorite one-size pocket diapers is made by Happy Cheeks.
I love this diaper. I reach for it first after washing the diapers. It's trim. It's well-made. It launders beautifully. I've never had a leak. I typically stuff it with a couple of thin hemp inserts and that does the trick for us and my heavy wetter.
The only two "cons" about this diaper are:
1. It says it's one size, but I don't think it would come anywhere close to fitting a thirty pound kid. I'll have to reevaluate this when/if L outgrows it, but it seems to be more like a "medium" than a small or a large.
2. The maker has decided to take a permanent internet/diaper making break. So you won't find this diaper for sale new anywhere. If you're interested, look for it in good or excellent used condition and go ahead and pick it up if you get the chance.
I paid $12 PPD for this diaper.
Lukas is three and a half months old and about sixteen pounds in this photo.