Including previews and/or reviews as I can find them…
For ongoings, Tiny Titans seems to be perennial hit with the younger set, which surprised me (in a good way!). Likewise Billy Batson and the Magic of Shazam!
The dinosaur-loving kid in me wants to recommend Age of Reptiles, but I’m not sure if six isn’t too young for a kid to see dinosaurs eating other dinosaurs. Might want to hold off on that one.
For collections:
Owly is adorable and suited for all ages, though maybe a bit lighter on the action than your son might like.
Lions, Tigers, and Bears has the protagonists collection of stuffed animals coming to life as the Night Pride to repel an invasion of monsters from under the bed. Cool adventure story, great art.
Eric Shanower and Skottie Young are doing a very well-received adaptation of the Wizard of Oz books that might be worth a look. Young’s art isn’t to my taste, but most kids seem to LOVE it. Likewise, Shanower’s new, self-illustrated Oz adventures are well worth picking up.
Instructions by Neil Gaiman isn’t a comic-book in the strictest sense, but an illustrated version of one of his shorter poems (found here). Basically, it’s all the best advice for what to do if you ever find yourself trapped in a fairy tale. Utterly charming.
For more straight-up superhero fare, the Marvel Adventures line mentioned above is a really good suggestion, particularly their Spider-Man and Iron Man books. Also, the X-Men: First Class and Wolverine: First Class books offer a good selection of superhero stories without the gore and angst that have been creeping into the main titles. Might be a bit wordy for a six-year old, though, even one who reads a lot.
Trickster is an anthology of Native American tales. It’s a lot of fun, the stories don’t get any longer than about seven pages each, and the talking animals might appeal.
I’d also recommend giving Usagi Yojimbo a shot – the adventures of a samurai rabbit might appeal to your son if he liked Captain Raptor. There’s some violence, but it’s all very cartoony – death gets marked by a skull and crossbones.
Hope some of that helps!