Not to boost David Mack's ego too much more, but he is also my favorite Trek author - by far.
Mack is in fact the only one whose books I will buy simply because he wrote them, it's the reason I picked up, Vanguard: Harbinger, SCE: Wildfire, The Calling, and Wolverine: Road of Bones (titles I wouldn't have picked up otherwise). Now, thanks to him, Vanguard is my favorite Trek series and while I haven't yet read Wildfire, I will likely read at least the others of that series that he wrote.
Next in line for me is KRAD. Like Mack, I have actively sought out other books he has written but still vet them based on what the back cover says the book is about - plus this guy's written a whole shit load of books in a whole shit load of series and I don't have time or interest in some of them.
Then there are the ones who have offered a mixed bag for me. Christopher L. Bennett who has two novels (TTN: Orion's Hounds and MyrU: Places of Exile) and a short story (VOY: Distant Shores: Brief Candle) that I LOVED and one book I couldn't even finish (TTN: Over a Torrent Sea). Andy Mangles and Michael Martin who are all over the board with greats such as TNG: Section 31: Rogue and ENT: The Good that Men Do to average ones such as their Titan entries and ENT: Kobayashi Maru to terrible ones such as their entries in the DS9 Relaunch.
The only author whose work I seem to consistently dislike is Peter David. Although I did like the short story in Tales of the Dominion War and the short novel in Mirror Universe: Obsidian Alliances.