I really don't like either of those couples. but ron and lavender dont have much in common so ya.

Neither. I have a huge dislike for both of these pairings.

Well at least Harry and Cho both play Quidditch and both as Seekers. Maybe it would have worked between them if the circumstances had been different (if Cedric hadn't just died, if Harry hadn't been totally unnerved by everything else that was going on,...). But even then I don't think it would have went without complications.

One of my favourite pairings. Don't really care much about the other one.

as said before, they have something in common. Lavender just loved Ron. (- and people say Harry&Ginny came out of the blue) she was okay in the start of the series. but turned annoying.

Cho was okay. it was annoying that she was crying all the time. but she had her reasons. i don't hate her because of it.

..

Defo Ron/Lavender.

Harry was with Cho because he genuinely liked her. He really was interested in her, and she was interested in him all the same.
Ron was with Lavender because (a) he was jealous of Hermione's contact with Viktor, and (b) he wanted to prove himself, to prove he was mature enough for a relationship, no matter who it was with (as Ginny had made fun of him for never being in one)
Also, Ron and Lavender's relationship was largely lust. Harry and Cho, although it couldn't really work, was actual love; it may have only been a teenage fleeting love, but it was love all the same.