I liked Clara until series 8's premiere, where she suddenly became shallow and nearly left the Doctor because he wasn't young anymore.
The companion I REALLY cannot stand is Amy, I despise her "I'm Scottish so I can slap people and get away with it tee-hee" (and it made me grind my teeth when Capaldi went "I'm Scottish, I can COMPLAIN!" and then "Oh, ~Amy~ would have been so awesome if she were here" - seriously, she's turning into Rose) and then she always treated Rory like an afterthought and tried to seduce the Doctor. I actually quit watching the show for a while (in the middle of the sixth series, after "Let's Kill Hitler").
SPOILERS
The companion I REALLY cannot stand is Amy, I despise her "I'm Scottish so I can slap people and get away with it tee-hee" (and it made me grind my teeth when Capaldi went "I'm Scottish, I can COMPLAIN!" and then "Oh, ~Amy~ would have been so awesome if she were here" - seriously, she's turning into Rose) and then she always treated Rory like an afterthought and tried to seduce the Doctor. I actually quit watching the show for a while (in the middle of the sixth series, after "Let's Kill Hitler").
Was also surprised to see all the Donna hate. :(