I tried making a list of my fave Elodie end-pairings, but let's just say it was inconvenient.
It's easier to name the ones I'm less fond of: Linley, Adair, and the Foreign Duke of Intrigue, mostly. (I ant my marriages of convenience to be with people I've annoyed during the game, thanks.)
Ignatius gets a special mention for having an epilogue I find very sweet when Elodie's an angel of music, and yet... this epilogue paints him in an unpleasant light as far as I'm concerned. (I killed your sister, Ignatius. The least you could do is poison me. Or attempt to kill me on our wedding night. Or, I don't know, politely turn me down while citing you don't actually resent what I did. Anciet doesn't marry me when I do away with his aunt or uncle, and the Good Lady knows he wasn't close to them by any measure!) Very sweet and very funny when Briony's alive, but I don't like to dwell on this outcome aside from that.
I'm inordinately fond of the endings where Banion and Elodie are on the same page - whether it's the flowerboy wedding or the affair behind Thaddeus' back. The more I play the more I like Banion, really, he's so terrible. It's not just that he's doing his utmost to marry Elodie evey way he can, it's that... so many of the things he does are dangerous or counter-productive. Why is he sending an assassin after you then disappointed if he accidentally kills you in a duel the vey next week? Why does he take Elodie up on her offer to carry on an affair behind Thaddeus' back? That's not the straight-forward powerpowerpower he aims for. Truth is, I think Banion likes complicated things. (My opinion on Banion is that he has way too much free time and has delegated the actual managing of his domain to a series of administrators that may or may not be embezzling wildly out of Maree's treasury.) His sneaky, smiling, intrigue-and-conversation back-and-forth interactions with Elodie make me very happy.

Also very very fond of the Brin, Banion-and-Brin, Briony, and Evrard endings. I adore the Kevan ending - whether it's normal Elodie or cruel Elodie. See what I meant about it being hard to choose? My favourite Thaddeus marriage is the angel of music version (so heartwarming!) - and, again, the one with the Banion affair. Which is still pretty heartwarming in a weird way and which can fit an OT3 narrative. I like Talarist when you choose him at the end of the game, especially when you've suspected him of having Adair killed. Anciet's epilogue is unbearably cute, as is the Earl of Pastry.
I haven't done as many variations about Brin as I'd like to - and so far most of my runs have been rather vanilla (aiming for Best Possible Endings and avoiding civil wars and rebellions and votes of no-confidence >_>), so there's still some room for things to evolve. I did get the incredibly bittersweet ending where Elodie marries Brin. The one I'm set on figuring out next is getting Joslyn to marry Brin so I can marry Banion without it turning into an OT3.
This did take a while.