The only characters from the BB pirates that I think could have a cool and interesting fight with Sanji is one of these two. Either Van Augur or Aokiji.
With Van Augur it'll be a fight of Teleportation vs movement speed. There is also the matter of Pudding kidnapping thematically connecting them. Don't forget Oda's first character imagination of Sanji was as a gunslinger so there is that too.
With Aokiji there is also the matter of Pudding kidnapping. And Five vs Ice sounds very cool.
As for the rest of the BB pirates, I really can't imagine a good Sanji fight with any of them.
First B is out of the question, he's Nika's fight.
Burgers is just too straight forward a fight for Sanji. Super kick vs Super Punch, boohoo. Most likely a Jinbei fight. A fight of the helmsman.
Shiryu is an invisible guy with a sword, enough said. Besides he's obviously the swordsman of the bunch, so he's reserved for Zoro.
Pizzaro is a hide and seek type of fight. More they alley of Usopp's kinda fight if you ask me. Usopp can see through objects with CoO, the perfect counter for Pizzaro.
Lafitter was my favorite in the past but nowadays no so much. What, he's fast? So? Sanji is fast too. But he can fly with wings man? So what? Sanji can run on the air. B-but he also can hypnotize people. Boo-f-in-hoo, Sanji's bullshit power of Love makes him immune to the Vinsmoke operation mind grape. So yeah, a fight with Sanji would be boring as hell. A former police officer vs thief thematic fight with Nami sound interesting though.
Caterina is a woman, enough said. She's obviously Robin's fight.
The drunk jester guy, for got his name, is just no. He's a paramecia Liquor man. Sanji's cigarette would low diff this guy, let alone DJ or IJ. Imo, he's most likely Btook's fight. And Ice vs fire and musician vs jester kinda fight could potentially be very intertaining to see.
Wolf is super meh. The only thing going for him is his size. The only good fight I see with him would be vs a megazoid with Franky inside of it. Inronically the mostt boring guy in OP could give us the best OP fight in history. OP very own Kaiju fight.
This leaves Doc Q. The guy is one step away from the grave. HeS obviously not a Frontline fighter. He'll get one shot basically by anyone ge5tong their hamd on him. I imagine his horse Stronger would do the majority of the fight with him being a support behind with his diseases. Sounds like a Chopper fight to me. Beast vs beast and doctor vs doctor, a two fights in one kinda deal.
So yeah, it's either Van Augur or Aokiji for Sanji. Aokiji is good guy obviously so my money is on the Van Augur right now. Black Leg vs Super Sonic.