This is for BEST. List not in any order.
1. Kai Winn. Great actor, great character.. every time I watch it I get the chills when she has the opportunity with Kira to change her direction and she does not. Seeing her with the disguised Dukat was beyond creepy, Trek's best train wreck you couldn't tear your eyes away from.
2. Gul Dukat. Unlike most people I loved his descent into cultish madness. He had a great character arc and a great ending. And more great--the acting again.
3. Quark. Fantastic, funny.. not a one schtick trick but a very developed character who had unique relationships with the other characters. Love interests, hate interests (Odo), family interests.. this guy has more going on than most Trek folk.
4. Odo. Quite unique, he could have ended up the Spock/7/Data character of DS9 but thankfully finding his humanity was only an adolescent phase. What we did get was the very interesting story of someone trying to find who he was with little to no reference points. A unique and original character who was able to surprise us.
5. Weyoun. I love this quote from Jeffery Combs about playing the character:
"So when the process started, I began to see how sort of royal and regal he was, and there was something kind of Japanese, but also he was the courtier in the court, he was the foppish, coiffed, graceful diplomat who would go from one party to another and make them all run smoothly. And he would do anything he could, with a smile, to make it look as easy as possible, and get exactly what he wanted. So I took a little spice from the French court as well.
I think Comb's character was a work of art, his best Trek role. And so much humor! Damar's hatred of him is fabulous.
Those would all be in my favorites list as well other than Odo who I never really liked. I'd have to replace him with Ezri in favorites