If yoou are still looking for comics...
The Carl Barks duck strips - though I wouldn't really give a six year old one of the hardback collections as those are rather pricey. Some of the thick 90s (Goldstone?) reprints in comic format would probably keep her happy. They really are remarkably well written for something that was aimed at children, and you'll find as much to enjoy as she will.
Batman Adventures (the spin-off from the 90s animated series) is great reading, even for adults, and if she likes the character it would be better for her than most of what is appearing from DC and Marvel at the moment. As an aside, what the hell has happened to plotting, character, and art in the last twenty-odd years? Sheesh.
I'm sorta in love with Doraemon, which is likely too cute for children, but damn, that is one funny little dude. Iznogoud is another character that will divide opinion, but it is often better than Asterix. Likewise Marsupilami, but good quality collections are thin on the ground - most of mine are falling apart rather depressingly.
If you can get your hands on either the Ewoks or Droids strips - based around the cartoons - those are massive fun, and you'll get her reading Star Wars, so... Win.

(My niece is ambivalent about SW, but my nephew likes the explosions and shooting in the films - big surprise there)