It is a popular choice, but I wouldn't put another album above it just because it's cliche. Anyone can be "one dimensional" depending on how you classify them. You could blanket all those "various issues" Cube touches on under "socially conscious rap" and claim that the whole album is socially conscious rap. That's why I don't base a rapper's range on one album because different albums can carry different stories.
Nas paints a perfect picture of life in Queensbridge and does it while staying technically sound, carrying a strong cadence, and a smooth flow. Illmatic is my GOAT because it's the perfect story. You could lay down, close your eyes, and let the music take over and just live through the songs. The entire album can actually lay a really chill, cold New York type atmosphere if you just listen and take it in. It's pure art.
But Death Certificate is not just "socially conscious", though. He also uses humor while addressing serious subjects and has fun in songs like "Givin' Up the Nappy Dug Out", "Steady Mobbin'" and "Doing Dumb Shit".
And about Illmatic, that's pretty much what I was saying. He just focuses on the streets and there really are no other subjects explored. And I can also find many other albums that "paint the perfect picture" of the rappers' neighborhoods. They may not be as good rapping wise, but they still get the job done to the same degree. Speaking of QB, that's pretty much also what Mobb Deep do in The Infamous. Don't get it twisted, though, I'm not knocking Illmatic at all, it's a great album and I can see why somebody would rate it highly. It's just that it's so cliché that you don't know how to differ between those who genuinely believe that and those that pick it just to go with the bandwagon.
Hell, I remember back in 2007 when I really got into hip-hop. I used to browse wikipedia and read articles about all kinds of subgenres and in almost every single one of them, the cover for Illmatic found its way there. It is the 2Pac of rap albums. Great but has led to lots of bandwagoning.
Lethal Injection wasn't that well received when it came out, but I liked it. But that was definiely the turn.
And he wasn't really gone for 5 years because the Westside Connection album happened in between. Between that, his Bootlegs and B-Sides and Featuring Ice Cube releases, and Sountrack appearances, it's like he was never gone. I mean, Lethal Injection went into 94 with the singles, Natural Born Killaz and Friday received heavy play in 94-95 and then Westside Connection came out and was massive in 96. So it wasn't all that weird or surprising when War and Peace dropped, Cube's music had changed a long time ago.
I don't know why I skipped Bow Down but yeah, I meant to mention it too as the album where he made some sort of transition. Although that one was so east/west focused that I just decided to talk about his official solos where it's more about Ice Cube himself than "the game". I also didn't count the Bootlegs & Featuring albums since they are just compilations of unreleased songs, b-sides, remixes or songs where he made guest appearances. But you have a point, it pales in comparison to the absence he had in the last decade when he moved on to making movies and occasional guest spots. (as well as a second Westside Connection album, let's not forget that)
Lethal Injection is still not well received to this day and I've heard lots of criticism for it, but for me, it works. "You Know How We Do It" is still a dope ass cruising jam. And the rest is on some chill shit which I always appreciate.