At the level of quality that Watchmen achieved? Not even V for Vendetta; Understanding Comics, maybe, I would need to read it again.
I got as much out of Stray Toasters as I got out of Watchmen, maybe even more. I think it's a criminally under-appreciated book. Your mileage may vary of course
Watchmen (as good as it is) isn't even Moore's strongest work IMO, I'd say From Hell is better.
Indeed it does, I place the earlier stories for Warrior, Moore wrote about both V and Miracleman, above From Hell. Other stand-alone stories, like The Anatomy Lesson, My Blue Heaven, Loving The Alien, For the Man Who Has Everything, Mortal Clay and The Big Chill also take precedence over it.
Frank Miller's Daredevil, Squadron Supreme by Mark Gruenwald, EC Comics Archives, James Robinson's Golden Age, Concrete by Paul Chadwick, Grendel by Matt Wagner,,, Underwater Welder by Jeff Lemire,
Pyongyang by Guy Delisle
Any of Will Eisners graphic novels
Louis Riel by Chester Brown (any if his books, actually)
Osamyu Tezukas adult books (Ode to Kirihito etc)
the complete essex county - jeff lemire (actually, anything by lemire)
i kill giants - joe kelly (this is a personal fav i recommend to everyone)
stitches - david small (because A+)
aesterios polyp - david mazzucchelli (the art is gorgeous and it's just so great)
I definitely think Daytripper could and should be on every shelf. I just picked it up the other day and finished it and it just blew me away. Absolutely amazing, stunning stuff with a lot of heart and a great message and story that I think everyone could relate to. Plus, the art is absolutely gorgeous and I think it would appeal to people who may like graphic novels but not superheroes, and even people who don't normally read comics. I thought it was that good.
Harley Quinn, New Suicide Squad, Grayson, Batgirl, Red Sonja, The Mighty Thor, Catwoman, Bitch Planet, Secret Six, Silk, Descender, Sabrina, Archie, JLA, DC Bombshells, Black Magick, Paper Girls, Tokyo Ghost, Vampirella, Scarlet Witch, A-Force, Extraordinary X-Men, X-Men '92, The Legend of Wonder Woman, All-New Wolverine, Power Rangers, Hellcat, Monstress, Descender
Too Cool to be Forgotten by Alex Robinson (or any of his stuff), Stuck Rubber Baby, anything by Joann Sfar