I'm pretty new to soap operas, but these are mine, these aren't neccesarily my favorite, but these are the most memorable. I think these kiddos belong together more than anyone else-
Victor & Nikki (Young and Restless) -ageless love, and definatly memorable; despite whatever happens, this mustach belongs with this former stripper. Whatever that new head writer has in mind, these two should end up with eachother.
Ethan & Theresa (Passions) -Starcrossed for eternity, torcherously redundant but you gotta admit, they are never ever gonna be forgotten. Theresa loves Ethan- we. get. it!
Carly & Jack (As The World Turns) -They get a little boring to me, but I can sortof see why people love these two together. Bad girl/hero passion/torcher is always a winner.
Lauren & Michael (Young & The Restless) My favorite couple, personally, 2 redeemed characters- one a former bitch/one a former bastard, together they are lovely fantastic fun. 
Luke & Laura (General Hospital) I never really got into this show, or these characters, but from what all I've read and heard about it in forums and boards, they DO belong together.
I'd also like Luke & Noah (As The World Turns) to become paragons of male/male romance for daytime. The show talks about committing to letting these gay characters be real, and staying on canvas, and not cowering away from them, so I can see it as a happening thing. Whether the actors stay or leave, the roles should be recast if and when. I can definatly see this couple in 20 years (should the show still survive on some soapnet or directv network or still CBS) as a couple men who's been through SEVERAL SEVERAL obsticles over the decades. Grey hairs, crows feet, still hot older gay super couple. I'd love it to happen, Luke/Noah is just what DAYTIME has been waiting for! But as for now, they're still pretty new to the scene, give it time, they'll become the next 'supercouple.'