It's very personal, so it really ought to be something that seems appealing. That said, some general guidelines: storebought diapers are pretty bad. That's not to say that you might not find your favorite thing at Walgreens but it's rare that those are really what we're looking for. Also, pull-ups are pretty terrible unless you're small. There's one ABDL pull-up (from Bambino) and it's worse than some of the regular pull-ups. The best products are purchased online and the most popular ones available in the US are ABUniverse.com, Northshorecare.com, and Tykables.com (alphabetical order, no preferences indicated). While each of them have AB diapers, they also have selections of more neutral from plain white to solid colors or patterns. There are other companies and other diapers but one or all of those are a good cross-section of what's available in disposables.
Should you decide to go with cloth, that's a whole other discussion and I'd suggest holding off on that until you get a little better acquainted unless those are really what seem like the ideal diaper to you.