Recently I've noticed a trend in my reading, which is that I'll read stuff that disappoints me (and some of which I don't finish, usually because I don't give a crap about the characters and their eventual fate) and need to read something better as a kind of palate cleanser. Getting rid of the taste of the mediocre with something that I know will be better.
In recent terms, my books of choice for resetting my mental palate have been the Vorkosigan books by Lois McMaster Bujold. I hardly know where to begin when talking about these books, because they are pretty consistently excellent in terms of their overall plots and the breadth and quality of their characters. I first came across them a few years back and had read the first few books but stopped for some reason - this time I've just finished book 12 of the existing 14 (with book 15 due for publication early next year).
While they are most easily described as a series, it's quite possible to 'dip into' the books at various points in their overall pattern, though I think you get more out of them if you run through them in terms of their internal chronology. Which is, alas, not the order they were actually published in. I have them in a combination of paperback and ebook (sometimes both!) and to be honest I mostly prefer the ebook because the paperback covers are pretty awful and off-putting. The artwork on some/most of them really doesn't reflect the quality of the writing, as at its worst it's bad 70's sci fi artwork, all busty women being protected by manly men with rayguns. That is emphatically not all there is to these books and so those covers do the books a disservice - as you'll discover when you read the books, the women you meet are very much capable of protecting themselves.
Your choices for starting points are pretty much either Shards of Honor (also published as Cordelia's Honor, in an edition that also includes the next book in the series, Barrayar), The Warrior's Apprentice, where we first meet Miles Vorkosigan, the main character in the rest of the books, or some folks have apparently jumped in a little later with Mirror Dance, which is where Miles first meets his clone-brother Mark (and hijinks ensue, as they often do in the vicinity of the Vorkosigans).
I can't recommend these books too highly. The world-building is excellent; Miles' home world of Barrayar has an obsession with social class and the military, while other worlds we encounter have all sorts of different takes on what it means to be human and what is important to them. If there's one thing I wish the author had explored, it is the truly alien - all of the worlds in her books are peopled by folks who originally came from Earth and we don't come across any sentient 'aliens', just the odd alien life-form. Likewise the characters are believable and realistic - while there are definitely villains, they are not stock moustache-twirlers, but people with their own understandable (if often wrong-headed) agendas, while the heroes (male and female alike) are no plaster saints.
And better yet, they stand up to re-reading, which not all books do - all of this makes them ideal for their role as a palate cleanser and I anticipate using them for this purpose for years to come...