Stand alones, especially ones that feature the Romulans or Klingons. Relationships over tech.
Okay, that helps immeasurably.
"A Rock and a Hard Place" by Peter David - fantastic interrelationships
"Metamorphosis" by Jean Lorrah - Data becomes human. Especially good if you've already read "Survivors" (1989, outside your date parameters)
"Vendetta" by Peter David - the big Borg sequel
"Q-in-Law" by Peter David - Q vs Mrs Troi,
'nuff said!
"Reunion" by Michael Jan Friedman - Picard's backstory
"Imzadi" by Peter David - the classic Riker/Troi romance story
"War Drums" by John Vornholt - Renegade Klingons
"The Romulan Stratagem" by Robert Greenberger - Sela and Romulans
"Triangle: Imzadi II" by Peter David - the big Riker/Troi/Worf unromance story.