For myself, I generally agree with Kav. But it's your collection, collect in the way you enjoy, of course.
But if you want the thoughts of other collectors, here's why I agree with Kav. 1) autographs to me are a memento of a personal encounter. (standing in line to hand Someone a check does not count for me.) 2) It is writing on the comic. It's damage. I don't want it.
My exceptions: the true personal encounter, with a book that's not worth much anyway, and plentiful (Herb Trimpe and Dan Green on my Godzillas) 2) I have a few that were parts of large collections that I bought that are on otherwise worthless comics and are kind of cool, but I do not consider them part of my collection proper, so much as conversation pieces. Examples: I bought an estate collection, and the guy clearly liked autographs. Stuff with COA got sold at auction, to people who enjoy them, to fund stuff I wanted in my collection. Stuff I kept is cool, unprovable (without spending $$), and on books no one cares about: all 3 Kuberts on some modern X-Men book they all worked on; Walt Simonson and Tony Isabella on some Topps comic, all 5 members of Aerosmith on that Shadowman they were in.
But that's me. Some people will pay more for autographs. I'm in the group that will look for a copy without it.