If I were a Studio executive, I'd make Dead Beat the first of my Harry Dresden movies. It is definitely my favorite of the early-Dresden books.
It has a lot of the world building already mapped out, but has plenty of surprises left to reveal. The ability to reference lots of previous events, people, etc. just make the Dresden-verse more 3D. Think of the references to the clone wars in the original Star Wars, the references to the old Republic, etc. it just made it seem like a real world. (This is one of the inevitable and unavoidable issues with the prequel trilogy).
Personally, I'd adapt Dresden as a mixed format series. The more traditional noir-detective stories (Storm Front, Fool Moon, Grave Peril, Death Masks, Proven Guilty, White Knight, Turn Coat, Cold Days, Skin Game, and even Peace Talks) would be adapted as television series. Summer Knight, Dead Beat, Changes, and Battle Ground would be 2-2.5 hour movies, since they're the ones with the big setpiece battles and are way more action-focused.
3-ish books per season, plus mini vignettes for the short stories, with a movie following each season. Really, the series is divvied up pretty well that way, in my opinion. And I'd rather we get it like that than the way they tried to do A Song of Ice and Fire (I didn't like the show. I liked the story of the books, but find Martin's prose to be extremely dull and unnecessarily pseudo-pornographic. Like... that's not what I'm here for). The last season was awful. A movie would've been better, because that, at least, carries a different set of expectations. You know, like not resolving an entire war, start to finish, in about 70 minutes. Compare to Helm's Deep and Pelennor Fields.