Log wise I'd especially recommend 7 & 8. ADF did a brilliant job with his expansion of "The Eye of the Beholder". The new material is one of my favourite trek stories.
I'd also recommend Log 10, which adapts "The Slaver Weapon" and adds quite a bit of new material to create a full novel-length story. The events of the TAS episode probably only comprise a quarter or so of the novel. Most of the weaknesses of the original episode are still present in the book, but the new material more than makes up for it. It was one of the first two Treklit books I ever owned (the other being Mudd's Angels
, both given to me in 1978), and it's still one of my personal favorites.