I suppose I should start by saying that I am a selfish person and there is a specific reason I read fanfiction. That reason is, quite simply, to get to see things I wanted to happen in series or books happen. While I'm a cynic, I am also a romantic, so for the most part this has to do with characters love lives for me. For example Buffy and Angel, who I believe belong together, period. I'm not saying I won't read other things, just that to me a big part of why I read is to see them get a resolution. Some of the pairings I support are not cannon (though most are) so fanfiction is even better then since there is little else that gives me those particular characters together. So since what is most important to me here is romance...

Pairings:

Buffy the Vampire Slayer/Angel: Buffy and Angel

Rurouni Kenshin: Kenshin and Kaoru

Slayers: Lina and Xellos

Daria: Trent and Daria

Pride and Prejudice: Elizabeth and Darcy

Please keep in mind these are my opinions, and therefore they are not subject to meeting your requirements of right and wrong, if you share my opinions great, if you don't fine, but please don't get mad at me for disagreeing with you. I do read out of other series sometimes, but these are the ones I feel most strongly about.