hm...good question.
Dragon Age Origins: Alistar. He annoyed me to no end. When forced to interact with him I was always a dick towards him.
Dragon Age 2: Humans, especially what's-her-name...the pirate wannabe. She reminded me of Megan Fox in that she always seemed look like she was sticky and, dirty. Don't care much for slutty girls either to be honest.
Fallout 3: I actually didn't use any of the companions until I ran into Fawkes. The dog seemed useless to me and I didn't want anyone else following me around.
Fallout New Vegas: What's-her-name from the Brotherhood of Steel. Love the Brotherhood but she seemed kind of bland.
Final Fantasy 7: I didn't care for Barrett or, Aerith to be honest. Nanaki was also someone I just couldn't get into. My party always ended up being Cloud, Yuffie and, Vincent.
Final Fantasy 8: I had a powerful dislike of the Laguna sections, mainly because of Ward. Kiros was freaking awesome though. I also kept Irvine out of my party after playthrough 2 or 3 (whichever one it was when I started paying attention to the story). You couldn't take the shot Irvine?! Well fine then, get the hell away from us and leave Selphie alone too!
Final Fantasy 9: Eiko for being annoying and, Freya. I never cared for Jumping and Dragoon powers.
Mass Effect: Humans. I want to be part of a massive space odyssey, I can't do that with a bunch of freaking humans all over the place and sharing in my wonderment.
Mass Effect 2: Same as above but since there are more aliens...no, still just humans. I should have used Thane a lot more than I did but Grunt is a tank and, Mordin is hilarious.
Knights of the Old Republic: For this one, I almost exclusively had another force-user and, a droid. I disliked Juhani and, Bastila. Carth was fine but I didn't care too much for him and Zalbaar...he can take his life-debt with Mission and just leave.
Sith Lords (KotOR 2): Atton, Handmaiden, Mira and, Visas. I never liked using any of them but, especially Atton. It's funny if he goes Sith but he turns into a freaking henchman.