Sanji would be the worst partner for anyone since he'd be flirting with other girls all the time
Well, it's also possible that if Sanji finally gets laid, he'd tone down his tendencies, like he probably won't stop complimenting and ogling other ladies, but will always get back to the girl who actually wants him? That's why I kinda ship him with Pudding (once she's legal age tho). I also think Pudding's evil persona will be watching out for Sanji not to cross a line, and he'll oblige. I used to be a hardcore SaNa shipper, but after WCI I think Pudding kinda fits better, Nami is a little too manipulative, and Sanji will always be a slave to her, with Pudding they're on more even ground as Pudding is head over heels in love with Sanji, and they might have a more balanced relationship. Although we need a time skip for them
As for LuNa, I think Luffy and Nami will continue the journey together, at least until the map of the world is complete, and will be forever partners, but I don't see their relationship being very romantic. I can kinda see Luffy and Nami being forever friends, not really settling with anyone.