Sanji Nami / Sanji Pudding and Luffy Hacock still has a valid degree of romantic interest which is missing in Lunami. If we are powerscaling in terms of chemistry and close moments than Luffy Zoro clears Luffy Nami hard
I just read it from Nami's end, and, to me, Nami acts like Luffy's wife. Nags him, worries about him, believes in him, and, as far as tag team fights, Nami is in her own category with Luffy.
Luffy and Nami vs Enel, and Luffy and Nami vs Cracker, pretty much proved to me that Nami is Luffy's Queen, and is best fit to stand beside him, because she compliments him so well. Also, no one else has interacted with Luffy's Straw Hat, his treasure, as much.
Luffy: no sense of direction.
Nami: master navigator.
Luffy: Doesn't give a shit about money
Nami: C.R.E.A.M. Cash rules everything around me, CREAM, get the money, dolla dolla bills ya'll
Luffy: MEAT
Nami: Fruit/Mikans
Luffy: reckless and easy going.
Nami: cautious and cunning.
They also have a lot of similarities
Both are loved by weather (Luffy with lightning in Loguetown, Nami all over the place).
Both love children (Nami and Luffy are pretty much Tama's surrogate parents on some level)
Both have a natural love for the sea and exploration
Both are very passionate and listen to their heart, even when it gets them into trouble
I just can't think of a female character that actually compliments Luffy better as a lover. And, since we all know how Oda feels about Nami, if anyone's getting with Luffy, it's Girl A: Nami.
I think we'll get a trigger soon to make Luffy realize how much he loves Nami... ie, Nami getting kidnapped by Blackbeard. Nami's navigational skills are very underrated, and, just as Robin was kidnapped for her ability to read the Poneglyphs, I think Nami will be kidnapped for her ability to navigate to Laugh Tale.