I think Hillerman was pretty sick for a number of his final publishing years. Starting with The Sinister Pig the stories started to get a bit weaker than the best earlier books, but frankly I loved the characters so much I didn't care. I generally don't get too involved in or enjoy the personal lives of the characters in mysteries much, but I admit to wishing Hillerman had time to finish another book or two and tell a bit more about the romance between Leaphorn and Prof. Bourbonette.
Although there are many "pretender"s I think only one current mystery writer comes close to Hillerman. The Walt Longmire mysteries by Craig Johnson, set on the Cheyenne reservation, are not quite as good as mysteries although the characters and Indian lore are every bit as good. The only thing currently being written that is as good, or better than Hillerman's books, as mysteries, are John Sanford's Virgil Flowers novels, but they're set in Minneapolis and lack the big sky country romance (but they are great police procedurals). I'm thinking: I could add Sanfords two heros: Lucas Davenport ($900 suits, Porsche 911) and Virgil Flowers (pickup truck pulling a fishing boat, even when he's on a case). I'll think about that.
But I will add Walt Longmire to my layout (its a very good A&E TV series now), or more specifically, Longmire (Robert Taylor) and his very cool friend Henry Standing Bear (Lou Diamond Phillips) and Henry's two cars, a completely trashed 4x4 named Rezdog that is just too cool, and a pristine '59 Thunderbird convertible.