ToS - None of 'um. I actually liked all of the main cast.
TNG - Wesley. I was neutral towards most of the crew, but he was just so painfully dull that I couldn't even bother pretending that I tolerated him.
DS9 - The entire crew. Seriously. I have no clue why, but I just couldn't get into the series. The first few episodes bored me to tears. Nothing really stood out to me and I ended up dropping it after the first 5 episodes.
VOY - Similar to ToS, I actually enjoyed or was just neutral towards most of the crew. The only one who bored me a few times was B'Elanna, but she's still a good character overall.