I think Tara was probably one of the most real characters on the show, I really have respect for that character for sure.
She showed true, human fear in "Family"-- she wasn't trying to hide a secret to fool anyone, she was just taken advantage of and scared like so many people are everyday.
She fell in love with Willow and was always there for her and the gang ("The Body" sticks out in my mind for this one, how she was there for Buffy even though she was almost the "odd one out", and she was always trying to make Dawn feel that much more included, somehow understanding her situation).
She also knew when to broke it off. I really respected her in "Tabula Rasa" when she did end it with Willow. It's something that a lot of people can't do in relationships, and I've seen a lot of lives go down hill because of it. She recognized that she was in something that wasn't healthy, and that it had to stop before it got anymore out of hand. Even though she loved Willow, she had the courage to leave. And not in the "I hate you I never want to talk to you again and hope you burn in hell b**ch!!" kind of way. She was still always concerned with how she was doing, not hateful just had a grasp on reality.
In my opinion, she's always been one of the most emotionally grown up characters on the show. She was rational and seemed to have this "human connection" to everyone in some way that you couldn't deny. She was the greatest friend: someone who would just listen without judging, who would help you out if you're in need (whether you asked for it or not) and she really had a deep respect for all the people she spent time with. And I think that because of what happened in her relationship with Willow, it really showed a very adult decision that made her perhaps one of the bravest characters on the show. She knew when it was time to leave, and she did it the right way. Without dragging everyone else into it, without all the drama, and not without warning. She gave Willow a chance, Willow blew it, and that was it. She was brave enough to walk away.
I'm a huge Tara fan, think I can also identify with her kind of shy exterior. Without a doubt though, my favourite character of the Buffyverse. 🙂