Look, before I start recommending any more books to people, let's talk about my hot buttons so you know when I'm recommending something that might not press your hot buttons.
Redemption. This is possible The Hugest thing for me. I'll read just about anything if there's a good redemption story. Now, you have to do it right-- if it's done clumsily (e.g., you must never ever actually USE the word redemption (unless, of course, you are Cordelia, who can somehow get away with that sort of thing), or have some dumb slogan like "Evil will turn in upon itself," because I will just laugh in your face) it will turn me off more than anything else-- and sometimes I'll see a redemption story where other people don't. To me, American Beauty, which in general I didn't like all that much, became at the end palatable because it became a story of redemption of the main character. This is what Cordwainer Smith and Bujold (two of my Favorite Authors Ever) are all about, and why I love Curse of Chalion-- which works as a redemption story both on the personal level and on the world/universe level-- to little bits and pieces. It's why Memory is my favorite Vorkosigan novel-- because the entire book is about screwing up, and redeeming yourself, and what it takes to do so.
Hard choices. This is a sister to redemption, because it's making the hard choice when everything in you wants to make the other one that does redeem you. (
mistful, guess which fic of yours is my favorite. Shouldn't be too hard. You will probably be able to guess my second favorite, too.) Extra points if both the choices are bad, like in Brust's Vlad novels. (That book-- Teckla, I think?-- is not fun to read, which is why I can't remember exactly which one it is, but it did give Vlad a depth that he didn't have before that.) Things like everyone going to face Sauron at the climax of LOTR, knowing they don't have a chance, count too.
Trust and betrayal; honor and dishonor. Again, you've got to do this right. A paper character who betrays another paper character for some flimsy motive? This will make me laugh rather than move me. (A good example of doing this badly is David Weber, who has Harrington say such howlers as, "But... we have to do it for the honor of the queen!" without actually, you know, grounding the world well enough that we understand what that means, or why it is important.) Rowling did it right in PoA. McKillip did it right in the Riddlemaster books. Honor, and honor betrayed, is a huge theme running through Bujold's books, and she does it really well.
Friendship/partnership. Especially synergistic partnership. I am a sucker when two or more people can work together like one entity. This is why I fell devastatingly in love with Firefly. Strong relationships in general will suck me in like nothing else. Vlad/Morrolan/Aliera is, despite all odds, such a partnership, which Brust only makes work because he is so danged good.
Growing up. In particular, seeing truths about the world you didn't see before. To Kill a Mockingbird is one of my favorites this way. The Chosen is pretty awesome too. Perilous Gard, as I've said before, almost deserves a special mention because its character absorbs some truths without even realizing she's doing so. Merry (one of my favorites!) in LOTR. Darcy and Elizabeth in Pride and Prejudice.
Knowing stuff about history I don't. Your characters may be paper-thin, your writing may be a little suspect, but if you've got a firmer grasp on history than I do I will read you and even enjoy it. (The firmer grasp of history will at least guarantee that you have good grammar-- I don't see how you could read all that history without picking up competent writing-- and a Plot, because history has the best plots.) Guy Gavriel Kay, who in general I have a hard time stomaching, won me with his Byzantium (sorry, Sarantium) novels. Kate Elliott, who has 2D characters and nonsensical relationships, kept me enthralled for 6 1/2 really thick books of medieval politics. (I skipped the half of the book where they go back in time for No Reason.) Patricia Kenneally, who writes rather floofily and New-Age-ily, and whom normally I would completely avoid, still manages to get me to read because she actually knows more about Celtic mythology/lit than I do. (And believe me, that is actually pretty difficult.) Part of my obsession with LOTR is that Tolkien knew, well, basically everything about medieval literature and history.
What makes you tick?