Different tastes for different people. Not everyone's going to like
Personally, I think Riker's just a jerk for the way he treats everyone outside the command clique that he's not trying to lay. He's consistently condescending and rude to them for no other reason than he can. So yeah, sorry... that doesn't win points with me. Especially when the script tries to tell you how likable he is all the time. Others like him because he is quite the loyal friend if you happen to be in his clique and that's their privilege.
Kira happens to be one of my favorite characters. Sure she's got a number of issues, but to me that just makes her more real. I'm sure if you drug a Jew out of a concentration camp in 1945 or just one that had been in hiding they'd have any number of issues too. She's been through a lot and isn't the everything's hunky dory picture that Star Trek often paints for the good guys.
Keiko... I dunno, she never much sold herself to me. It's not that she get annoyed with O'brien occasionally... it's that she complains almost every episode she's in about O'brien's career and what she gave up for him, what he's doing. She does come across as a nag of the first order to me. But that's not all there is to her by a long shot. By all accounts she does seem to be a very compassionate person who cares about the people around her. My favorite scene with her is when she was telling O'brien to "kick his butt" in Rivals. You just got the feeling she was behind O'brien there.
Either way, you can go down the list with any number of characters and opinions are going to vary with each board member here. Just the way things go.