Best books for young boys?

Hey everyone! I’m looking for some fun book suggestions for a 6 year old, ideally something a bit above his reading level. He has a younger brother, so they already share plenty of picture books, and while I think picture books are great, I don’t want him limited to only those. I’d love to give him something he can grow into rather than outgrow quickly.

I think for any book lover we can remember the person who built our love for reading and I would love to do that for him.

His dad already reads chapter books to him every night, so this wouldn’t be for independent reading yet. Graphic novels would be ideal, but chapter books are great too.

So far I’ve gifted him “The Phantom Tollbooth”and the picture book “Theodore and the Cat with the Missing Sock”, I don’t know if his parents have read them to him yet or if he even liked them. I think he’d enjoy something with a little more action. He’s currently really into superheroes and cars, though I’d prefer not to limit him to just Batman or car-themed picture books. I’m hoping to help nurture his love of reading, adventure, and imagination.

I’ve considered the Dog Man or Captain Underpants series since a graphic novel format seems like a great bridge between picture books and chapter books. But I don’t think his mom would be a fan, and I’d rather avoid potty humor or intentionally misspelled words at this age. Maybe when he’s older. I’ve also looked at “The Magic Tree House” series and “The Little Grey Men”, (the classics of course) but I’m wondering if there’s something with a bit more “oomph” that would really grab him.

Throw me your recommendations, classics or your personal favorites!