Online Masters, a degree-touting site, has an article that lists the 40 Best for the Classroom.
I think calling them comic books is going outside the level I would teach. For instance, I wouldn’t teach Asterix (39) and TinTin (30) anywhere but a French classroom. However, there are others I would use.
Last year I attended a talk at SCMLA on Persepolis (1) and have seen several on Maus (2). Watchmen (3) and V for Vendetta (13) have been discussed various places, though I don’t think I’ve seen a teacher talking about them. I have heard Sandman (16) and American-Born Chinese (23) talked about for classroom work.
Even if you aren’t sure about the works, at least the list gives you some to look at.