Garak is excellent. Poignant, enigmatic, and cleverly written. Was meant to be a one off originally, but Andrew J. Robinson nailed it. He's even written a few Garak novels, which I've not read admittedly. Another Cardassian character I love is Damar, his utilization shows the writer's talent, that a barely background character becomes one of the most affecting, to me at least. The scenes in Garak's former maid's basement with Damar are full of charm, wit and pathos.
My last watch through was last year, and I have to say it was probably my favourite. All the characters come into their own, and have satisfying arcs. Even the side characters are well rounded, all written and played with such obvious love and passion. I love the performances of Jeffrey Combs more and more each time.
Also I really like the space battles, with the booms, and the lasers, and the explosive decompression.