And yes, this is as subjective as all hell.
Harvest Is When I Need You The Most - A very unofficial Star Wars mini-comic created by a group of talented creators. At times funny, sweet, surprising, and artsy, but always a lot of fun.
The Order - Probably the best Marvel ongoing series since Nextwave: Agents of HATE, and just as undeservedly cut down before its time (allegedly by writer Matt Fraction himself, but that doesn't make the loss any easier). Superheroes-as-celebrities is nothing new, but Fraction really got into these characters' heads and really gave them life.
Comic Book Comics - Not a definitive history of comics, even by the admissions of Fred Van Lente and Ryan Dunlavey, but solidly entertaining. A good starting point for people who want to learn more about the history of the medium, but still quite informative for the already-initiated, too.
Captain America - Look, someone had bet me 5 years ago that they'd not only bring back Bucky, but bring him back as a bad-ass cyborg Cold War-era Soviet assassin, then make him the new Captain America, and that it'd actually be a good story, well, I'd have lost that bet, and damn badly at that.
Marina: A 24 Hour Comic - Pure joy in black & white comic form. Read it for yourself. Then go buy a copy (if the website's up, anyway). It's a dollar well-spent.
All Star Superman - This is not the greatest Superman story in the world, no, this is just a tribute. Except that even in tribute, Morrison and Quitely created something so transcendent and wonderful that it sort of comes back around and actually eclipses the very work they tried to emulate. I think they were shooting for Maggin but wound up at Moore. Not that there's anything wrong with either destination, mind you. I'm rambling now. This was great. 'Nuff said.
Skyscrapers of the Midwest hardcover - Months later, and I still think of this book frequently. It's sad, it's funny, it's downright unsettling. Metaphorical as it may be, it still gets early adolescence exactly right, for better
Herbie Archives Vol. 1 - So look... if you can find no joy in Herbie, I don't think we can be friends.
And there are honorable mentions to be sure... The Umbrella Academy: Apocalypse Suite, Brand New Day Spidey, the Queen & Country Definitive Editions, and The Age of the Sentry all come to mind. But as far as what I liked best, yeah, the above is pretty much it.