For iOS, there's a DC Comics app, a Marvel Comics app, an IDW Comics app, and an Image Comics app (as well as others like Dark Horse and Disney).
However, there's also a Comixology App that includes DC, Marvel, IDW, Image, and various others, and it looks like many (maybe all?) of those publisher apps are based on the same code as the Comixology app (some of the descriptions explicitly mention being powered by the Comixology technology).
There's obviously an advantage to reading in the Comixology app: it's possible to use one app to read across many publishers. Are there any reasons to read in the individual apps instead? For example, do I get a better experience somehow reading Spider-Man in the Marvel app?
I presume the actual comic images are 100% identical, so benefits would have to be in the interaction (except that I think this is what's common), or something other than the reading experience (like additional information or notifications or related material).