Yeah even Marco, the highest Yonko commander bounty revealed thus far is at 1.374 billion, just 54 million more above Queen's, and Marco he was the strongest member under whitebeard. That's impressive considering the Beast Pirates bounties could already be slightly inflated because of their viciousness and attack on civilians. The fact that Marco has been inactive for 2 years and Queen still hasn't managed to pass his bounty means a lot.
Sanji's bounty from 77 million to 177 was already inflated because of his family, and he got another raise to 330 million for defeating no one important in WCI.
Luffy's 1.5 billion bounty already makes him the 5th emperor, no other yonko commander shown thus far have a higher bounty than Luffy, meanwhile Teach the new Yonko only has a bounty of 2.24 billion.
Both King and Marco should have higher bounties than Queen, but even King might not be as high as Luffy's, even if he is- i would guess its at 1.6 billion at best. Sanji getting 1.5 billion would be quite unrealistic, because Luffy had to do a lot more than just beating a yc1 commander (not even y2 commander like Queen is) to get to 1.5 billion.
Defeating 2 commanders, having a grand fleet, plus also the fact that Luffy's 1.5 billion is long overdue payment for his hidden accomplishments for defeating moria, infiltrating impel down, participating in marineford war, being dragon's son etc. Luffy's big raise was overdue even before WCI and was a long time coming.
Sanji just beating Queen and getting 1.5 billion makes Luffy's accomplishments look like they aren't worth spit in helping him reach 1.5 billion.