Oliva Reed. Only because she had the smallest importance in my opinion. I couldn't pick either of the Drevko sisters even though they were EVIL! And Lauren is my all time favorite character so I there was no way I was going to pick her!
Even though Lauren was evil, she was a good for the plotline. And Olivia was too insignificant to waste energy on. I hated Allison. She killed Francie and she "got together" with Will. And she keeps coming back!!! Just stay dead already
Sloane, the character outlived his usefulness very quickly, he should have been killed in season 3. Having him run APO was ridiculous, and his reform bullshit was just boring and took way too much screen time