27. Earth X
by Alex Ross and Jim Krueger
Published by Marvel Comics
I'm came to reading alternate histories by reading alternate futures first, as tends to be the way of comics, particularly in the 80s and 90s.
Earth X has everything that a good -- no, great -- alternate future story needs: a fun story, a quest worth enduring, and the beautifully painted art of Alex Ross.
The other books in the series, Universe X and Paradise X, are also strong reads, but neither quite pack the punch of this opening volume, nor do you need to read the follow-up volumes in order to enjoy this opening volley.
For the "rules" I'm using for graphic novel, check the original post.