I've spent a bit of time comparing the early pages of Burton Raffel's decade-old rendition with Edith Grossman's brand new one. Both are excellent, so you can't go wrong---and I think either would be a better choice for most people than past translations. I've chosen Raffel's, though, based not only on word choices (and I think some people need to lower their antennae when it comes to things such as Sancho referring to his "kids", which seems quite natural), but on Raffel's better balanced, more focused style, and his clarity of phrasing (which also involves word choices). Raffel's style overall is traditional. Grossman seems to jump between the literal, which is sometimes confusing, and the breezy and modern, which is enjoyable but not as wry and witty as Raffel's balanced approach.
For example, Grossman's description after our hero has tried to grapple with the philosophical convolutions of de Silva: "With these words and phrases the poor gentleman lost his mind, and he spent sleepless nights trying to understand them, and extract their meaning. . . ." Raffel writes: "Arguments like these cost the poor gentleman his sanity; he'd lie awake at night, trying to understand them, to puzzle out their meaning. . . ." A minor example, but with Raffel's rhythm and word choice you can almost visualize the old fellow lying awake trying to "puzzle out" the "arguments"---not just "words and phrases," per se. Raffel is often more subtly attuned. Notice also that "cost the poor gentleman his sanity" is not as modern-sounding as "lost his mind." So don't think that because Raffel uses a few modern word choices for the sake of vigor that he's less distinguished.
Grossman again:
"His fantasy filled with everything he had read in his books, enchantments as well as combats, battles, challenges, wounds, courtings, loves, torments, and other impossible foolishness, and he became so convinced in his imagination of the truth of all the countless grandiloquent and false inventions he read that for him no history in the world was truer."
Raffel:
"He filled his imagination full to bursting with everything he read in his books, from witchcraft to duels, battles, challenges, wounds, flirtations, love affairs, anguish, and impossible foolishness, packing it all so firmly into his head that these sensational schemes and dreams became the literal truth and, as far as he was concerned, there were no more certain histories anywhere on earth."
Grossman's sentence is more difficult to scan, and less concrete. Raffel's clear, no less fine prose in paragraphs like this brings the character of Don Quixote to life.