Ah, a classic from the "Marvel Alterniverse" line spawned by Marvels, The Last Avengers Story is a two-issue prestige format series written by Peter David with painted art by Ariel Olivetti that has a certain Kevin O'Neill feel to it.
The basic plot: sometime in the future, superheroes don't do much except sit around and shoot the shit. Years ago, the government had the superheroes do a country-wide search and capture to eliminate the supervillain population. The catch was the heroes thought the villains were going to prison, while the government turned around and killed them all. That pretty much made most of the heroes we know and love quit the game right then and there.
Until Ultron shows up and blows up the current Avengers and then visits Hank Pym to challenge him to a final Avengers/Masters of Evil showdown. Ultron has Kang, the Grim Reaper and Oddball, while Pym must try and gather what heroes he can, because if he doesn't, Ultron is just going to go around and kill them anyway.
Most of the appeal to this series lies in that glimpse into a possible future where Peter Parker and Mary Jane have a teenage son or Wyatt Wingfoot and She-Hulk had a daughter who took after her mom. Or how Thor, Hercules and the Thing all died in some sort of god-related battle, while the Hulk somehow survived but not unchanged.
Or, the horrible final fates of Quicksilver, the Scarlet Witch and the Vision--and the effect it had on Tommy and Billy, their sons.
It's a good read with some interesting bits. I figure that one of my favourite ideas, "superheroes react, while villains ACT" was actually stolen from here (although, David probably didn't come up with it either, but I read this when I was younger and it probably got stuck in my brain).
In a way, this is a good cross between Marvels and Ruins. It is very loyal to what came before, but also has a rather fucked up realistic bent. It almost seems to be a warning to writers tempted to push the group down these paths. It was published in late 1995, still very much in the midst of all the darker 1980s/90s bullshit. Of course, since then, various storylines have occurred that could produce such a depressing, bleak fucking future as presented here--although, it isn't all bad, as Pym notes: Peter Parker has found peace. Who would have thought that? The only hero to find true peace in the Marvel universe is Spider-Man. Gotta love PAD's sense of humour, eh?