Taste in books is individual and I don't like choosing favorites, but Patricia Briggs is likely my favorite "Urban Fantasy" author.
Frost Burned is #6 (of #9) in the Mercy Thompson Series. Long series are a challenge. Authors often improve as they write more, and character develop and become old friends, so quality often improves after the first book or two. That is balanced by the urge to spend excessive time on flashbacks and allusions to what has gone before and managing the proliferation of key characters, so eventually most series go stale. Frost Burned is a nice balance between these competing items. It's far enough into the series that the world and characters are well developed, but things are not yet stale.