I once saw a manga called Red Sun, which looked like a Japanese version of Red Dawn, with North Korea invading them. I haven't been able to find it since (even though I've lived in Japan for almost a year) and it's driving me insane.
Anyway, my own ideas, for what they're worth (warning, mostly British and old)
Action:
Commando comics, 1961-present. God knows which of the 5000+ issues it should be narrowed down to, but people who live in the UK can't go wrong with picking up a "gold collection" issue. Elsewhere, look for the True Brit compilation book from around 2006. Mustang Ace is a cracker.
Judge Dredd: The Pit, great introduction to the character, awesome firefight at the end
Adventure:
Tintin, obviously
Modesty Blaise. I've far from read all of them, but I remember the book containing Mister Sun (and 2-3 other stories) being a good 'un
Dan Dare. The 1950 - 1969 version, and especially the Frank Hampson years. If you want to narrow it down further, the first three Titan volumes, encompassing the first two stories.
Comedy:
Viz
Drama:
Pre-code EC of various moulds. The fantagraphics book Came The Dawn has some of the most infamous "preachies" in it. They trigger my inner Holla Forumsack, but they were written by guys who lived in all white, picket-fenced suburbs. They didn't know any better.
Roy of the Rovers - The Best of the 1980's
Horror
Fuck knows. Some Misty, maybe? British proto-tumblrists discovered Misty a decade back, and heralded it as some amazing feminist comic which, "if it had only been given a chance" could have changed the course of comics history, taken the place of 2000AD, and make comics a girls-only thing which only had male involvement on the fringes. In the real world, Misty was IPC's response to DC Thomson's Spellbound, an also girl-targeted, horror-themed comic which came out a few months earlier. Neither lasted very long because, while girls did read comics in that time and place (allegedly more than boys, but the cold hard figures aren't available), they still think spiders are icky. Anyway, Misty's fame is blown out of all proportion to the Goosebumps-tier style of most of the writing.
Strips
Dilbert. If only because Scott Adams triggers the fuck out of SJW's on a regular basis.
Superhero
I hardly read them. But I marathoned the first Essentials volume of Fantastic Four one day when there was an epic traffic fuckup. The first Avengers volume is alright too, in limited doses. Some of these chucked-out, phonebook-style black and white volumes are reaching silly prices, now that they're out of print, mind you (you'd think that might tell Marvel something). I once had the chance to buy a shitload of them for £5 each, still pissed off with myself.