Relatable characters (or well-written), excellent writing, good spelling, & well researched. Repetitive writing is jarring, as is the obvious use of a thesaurus.

I was reading a book years ago, & one of the characters "escaped" to Toronto, Ontario, Canada. Then took a 2-hour drive to Whitehorse, Yukon Territory! It was a minor plot-point, but still! I shut the book, & threw it into the "Salvation Army" box. I don't recall the name of book or author, but being THAT incorrect pulled me entirely out of the story! (A ✈️ flight from Toronto to Whitehorse would be minimum 6 hours, with at least 1 layover!)