(Ok, the tag "How I love them... let me count the ways..." is a bit of an exaggeration, but I couldn't think of a snappy phrase.)
Before I start with Cedric and Cho, let me say...
On the rare pairings side (pre-CC), I actually didn't have a favorite. I liked Harry and Hermione's friendship/relationship and am
Onto Cedric and Cho...
Let me first say, I watched the first three movies before I read the books. And I read the books because I wanted to know what all the hype was about. I started with GoF because I was curious how the movie would turn out, went to OoTP, then HBP, then back-tracked to the first three to compare them against their movie counterparts.
It started with Cho. I admit - I was not a fan of book!Cho. To be honest, neither book!Cho nor book!Cedric left a lasting impression on me. I saw them as one-dimensional background characters. I did not cry when Cedric died; in the book, to me, it was 'next chapter. wormtail zaps cedric. cedric dead. now onto harry.' (correct me if I'm wrong as I haven't read the book in over a year? but I think his death was the first one or maybe two paragraphs of the beginning of the chapter.) So, I was like - 'ok, next?' As for book!Cho, she flickers in for two sentences than leaves. Of course, she had more to do in OoTP, but it was disconcerting to me. Me: 'Oh, she's crying? Why is she crying? Oh! It's because of Cedric? Hmm.. what page am I at? what's the timeline here? Is it January and she's still crying? Oh! Why is she asking Harry about him?' So... basically, I had no feelings for either character.
Then, my mother tells me a cute Chinese girl was chosen to play Cho. 'Oh! Really? Cool.' So, I looked up Katie, as well as started to look for Cho articles/fanfics on the internet. Now, here is the 'strange' thing... It was actually the Cho-haters who made me start to like her.
(No, I don't mind if you "hate" her because she cried a lot or dated Harry when she wasn't over Cedric; I only minded the Cho-hater comments that called her a 'ho/whore/slut' who 'stole Harry's mouth virginity' who used Harry because she only wanted to date popular guys, blah blah blah -- and by extension those Cho-haters who are also Katie-haters merely because they are jealous she will kiss Daniel in the next film.)
I couldn't (can't) understand those haters. She's a one-dimensional character for goodness sake! Give Harry SOME credit - do you think he has bad taste? She was nice, she was pretty, she was 'popular', she had to be smart to be in Ravenclaw. She didn't wear a 'Harry Potter stinks!' button; she didn't laugh at him. /gets off soapbox.
Back to CC... so I started empathizing with Cho... and by extension, I started to like Cedric. He must have been special to Cho if Cho kept crying for him. I started looking for fanfics/fanart revolving around the couple... I wanted to know the story behind the story. Of course, that is up to the writer's imagination. (And this is the time that GoF came out, and the actors do make a beautiful couple on-screen and off.)
To me, they are an idealistic couple. Both 'handsome/beautiful', smart, athletic, friendly/nice (that is, neither of them were mean to Harry). Cedric chose her for his second task; that must mean he cares about her too. They represent the 'first love' ideal, because when you fall in love for the first time, you think it's forever. You put your whole heart into it.
Side note: I think I have a thing for tragic love (see my past obsession with Sailor Moon's Inner Senshi/Shitennou).
As for Draco/Cho, I stumbled upon that even-rarer-ship while I was searching for Cho articles/fics. I crossed into and read halrloprillalar's fic because it dealt with Cho moving on after Cedric's death. It has a bit Harry/Draco in it (which I didn't mind) and it was nicely written. As Ravenclaws are the only ones who will consider dating Slytherins (besides other Slytherins), I thought it might fit. Despite the fact that he's in every book, Draco remains one-dimensional. There might be layers to his personality (a fanfic writer's dream/imagination). I wouldn't go for the Cho-hates-Harry-so-dates-Draco-for-reven