The only TNG book I can remember reading is The Devil's Heart, but that was probably 20 years ago. Hard to really give a fair opinion on it being that long ago, but from the small plot summary (that I would post if not on my phone) I think I enjoyed it.
Also read a couple of TOS books including Probe, which was the continuation of Star Trek IV and explored the origins of the Probe. It was kind of boring.
Only read one DS9 novel and would need to be at home and check my bookcase to see which