Ron/Hermione: Perfect couple. I always hoped they would realize their love for each other, but it was so obvious in the 6th book.
Harry/Ginny: Eh. It's really cute, and I don't exactly hate it or anything like that, but it's not one of my favorites. It's went too fast, and it's too much of a "star-struck" relationship. Ginny liked Harry at first just because he was famous. It's lust, not love.
Lupin/Tonks: Kinda random, but not bad! Interesting love twist...
Hermione/Draco: Great to read in fanfiction, but will it happen? I highly doubt it.
My OTP (one true paring) : Fred/Angelina. Perfect, perfect, perfect! She laughs at his jokes, they both play Quidditch, he asked her to the Ball in the cutest way. I really want it to happen
There's also the theory that Snape was in love with Lily...