no prep , in character , Round 1 - pre time skip sanji , Round 2 - current sanji
Location - Warship Island
^ I don't feel he is behind at all. He can defeat a pacifista.
He was the one kicking that giant puffer fish alone with leg strength casually.
And he exhausted himself in nami's body and nami was using his body.
And he is confident about launching an attack at big mom.
Well It isn't surprising that sanji had trouble with virgo considering virgo was a master of armament haki. Not all marines master it to the extent he did. Heck he is the only person who has shown enough mastery to coat his entire body in it.
At this current point in the series I don't think zoro is stronger than luffy.