Velanna, Vivienne, Sebastian, and Carver.
I loved Isabela the first time I played, then the next few times I started to not like her because she kept betraying me because I didn't get her approval up high enough. Finally fixed that the last time I played but those previous experiences really left a bad taste in my mouth. I still like her, just don't love her like I did.
Sebastian is everything I hate in a guy (minus the mommy's boy thing) wrapped in a package with pretty eyes and a nice accent. I'm sooooo glad I didn't get his DLC. Seriously. 
Velanna was a b*tch and just wasn't interesting in the slightest. Did she have any character growth in Awakenings, 'cause I can't remember it.
Vivienne is a b*tch too, but a well written one. She had points that I could respect even though I disagreed with her. She just kept disapproving of almost everything I did and I will never compromise my position just to satisfy her. I did a playthrough recently where I didn't let her join the Inquisition, but it felt kinda hollow. I missed seeing the Vivienne Disapproves in the corner of my screen. I actually like having someone there who doesn't get along with my Inq. Adds to the experience. 
Carver was really well done. His antagonistic relationship with Hawke is the polar opposite one to what Hawke has with Bethany and it forms an interesting sibling dynamic. Seeing it this relationship change and adapt as the years went by and how Carver's able to grow into a role he feels at home in is rewarding. However, like Vivienne, I do not like him but I came to respect him and I could understand how he felt.