I'll hop in because, might as well.
As others have said, yep, those three brands all share the same basic make and fit, it really is just the prints or lack there of that are different.
Having tried all 3, I love em all. I like the prints on Little Pawz and Space, although the Space diapers feel like more of a Toddler diaper, the Little Pawz designs are much more cuter and babyish in my opinion and there's something nostalgic about the simple, an all-white AB diaper.
Yes the print can rub off, but as Argent notes above that's only a legitimate concern when oils or creams are applied. I'd say if you stick to using a standard rash cream and powder you're fine, but if you use baby oil, then yeah, you might have the print rub off on something like your clothes, bedding or onesie... not fun
The Absorbency is great, I think only 2 other brands can boast the absorbency that ABU has, Tykables and Rearz and personally, I prefer the fit of ABU brands to both Tykables and Rearz. ABU is also the perfect thickness level to me and they swell quite nicely too, not unlike a Crinklz.
All in all, 3 great diapers. It really comes down to personal preference as to which ones you'll order a bunch of. If you're into a more contemporary Baby/Toddler diaper with fade when wet decals and babyish prints, then Little Pawz or Space will go a long way. If you're into something that's a bit more of a throwback and a little simpler, more utilitarian, then the all white ABU Simple is a good way to go.
Whatever you decide on, you're bound to be getting some good diapers and some quality ABDL time