Well, not this Sunday. That would be silly. SF Signal posted these questions two weeks ago, and I'm posting my responses now, because that's how we do things here at Kaedrin.
My favorite alien invasion book or series is...?
All the examples that are coming to mind seem like borderline cases. Is Ender's Game an alien invasion book? The story is set into motion by an invasion, but you don't actually see it (Ender reviews recordings of it). How about Anathem? That one seems even more borderline (Are they aliens? Are they actually "invading"?), though if it does qualify, it'd probably be my favorite. What can I say, I'm a Neal Stephenson junkie. This... may come up again.
My favorite alternate history book or series is...?
While I can't say as though I've really delved into the alternate history sub-genre, the two books that come to mind immediately are Michael Chabon's The Yiddish Policeman's Union and Phillip K. Dick's The Man in the High Castle. The latter of which has the more clever premise (indeed, it's got an almost recursive structure) and is clearly more influential (it's among the early examples of a "what if the Axis won WWII?" story), but the former is a much more enjoyable read (basically a neo-noir style detective story).
My favorite cyberpunk book or series is...?
Here comes Stephenson again: Snow Crash. Of course, he was sorta taking the piss out of the sub-genre and even kinda killed it, but that's sorta why I like it, as I'm not a huge fan of cyberpunk. William Gibson's Neuromancer is a worthy runner-up here, though it's still not really a novel that I love.
My favorite Dystopian book or series is...?
Another sub-genre I'm not a huge fan of, yet the answer is blindingly obvious: Nineteen Eighty Four by George Orwell.
My favorite Golden-Age sf book or series is...?
The start of the Golden-Age is pretty easy to pinpoint - when John W. Campbell became the editor for Astounding Science Fiction magazine in the late 1930s. When the Golden-Age ends is more vague. I'll place the line of demarcation at 1960. It's an arbitrary choice, but it seems to work. However, given that constraint, the first book that came to mind (a Heinlein) is no longer eligible! So what I'm left with is a bunch of Asimov, which I do love despite the distinctly wooden nature of his prose, and a bunch of other one-offs. The two that seem to be winning the battle are Arthur C. Clarke's The City and the Stars (1956) and Theodore Sturgeon's More than Human (1953).
My favorite hard sf book or series is...?
My answer here is going to be an author, because I can't think of anyone who writes hard SF at the level of Greg Egan (I'm sure they exist, I just haven't read them). Egan's books make me question whether or not I've ever read hard SF before. So to narrow it down a bit, I'll go with Diaspora. The hardest of SF, with an ambitious and truly astounding scope. (For something a little more approachable, Permutation City works pretty well, while still being "hard").
My favorite military sf book or series is...?
In terms of straight up military SF, I'll go with Old Man's War, by John Scalzi. Though Starship Troopers and The Forever War are clearly more influential and "important", they both have pretty heavy flaws (Heinlein's incessant lecturing, Haldeman's treatment of sexuality). I suppose you could say that Old Man's War is a little on the light and fluffy side, but I think it works pretty well.
My favorite near-future book or series is...?
I want to put Cryptonomicon here because it's Stephenson and my favorite book, but it's only debatably a near-future book (it's unspecified, but the implications are present-day or very-near-future), and even the near-future stuff is only half the book (with the other half being set in WWII). That being said, I'm keeping it here, because why not?
My favorite post-apocalyptic book or series is...?
The two that come immediately to mind are Stephen King's The Stand and Richard Matheson's I Am Legend. Both books suffer from poor adaptations into film/TV, but are excellent in their own right and well worth reading.
My favorite robot/android book or series is...?
Asimov's Robot Series pretty much takes the cake here. I can think of lots of other books that feature robots, but they're usually just window dressing. Asimov's robots aren't truly about robots either, I guess, but I love the way he starts from basic principles (the three laws of robotics) and sets about subverting them at every turn.
My favorite space opera book or series is...?
Lois McMaster Bujold's Vorkosigan Saga. I was tempted to put this for the military SF question, because there is a fair amount of that going on in the series, but it's really much more of a space opera than a military series (even if there are a lot of military SF elements).
My favorite steampunk book or series is...?
I don't really do steampunk, so I don't really have anything to pull from here. Mulligan!
My favorite superhero book or series is...?
My love of Batman is probably more due to The Animated Series and the movies, but I've read some of the comics too, which is more than can be said for most superheroes.
My favorite time travel book or series is...?
Yikes, a suprising amount of choices here. Asimov's The End of Eternity and Dean Koontz' Lightning (the book that got me into reading when I was a youngin) both spring to mind. Downtiming the Night Side by Jack Chalker takes things in extremely weird directions, but I enjoyed it. There's probably a dozen others I could list (or want to read), as this is a favorite sub-genre.
My favorite young adult sf book or series is...?
My first thought here was Heinlein's juveniles, stuff like Have Spacesuit, Will Travel and Tunnel in the Sky. Then I remembered Madeleine L'Engle's A Wrinkle in Time, which is clearly the best choice.
My favorite zombie book or series is...?
I kinda hate zombie stories, so they're not something I really seek out in book form. The closest thing I've read to this would be the aforementioned I Am Legend (which are vampires, but the story contains many tropes that would become common in zombie stories).
The 3 books at the top of my sf/f/h to-be-read pile are...?
Well, it's a long list, but three upcoming books: Paladin of Souls by Lois McMaster Bujold, Consider Phlebas by Iain M. Banks, and Warhorse by Timothy Zahn.
So that just about covers it. Lessons learned: I have a hard time choosing a favorite novel (most answers above list 2 books, if not more), and I'm not super well read in every sub-genre. Heh.
Update: scepticsmiscellanea gives answers. Warning: We've got another Stephenson/Bujold junkie here, so yeah, some overlap with my answers.