Luffy (Captain)
Zoro (Vice Captain)
Sanji, Jinbe, Yamato (Monster Trio)
Franky, Robin, Brook (Mid Trio)
Chopper, Nami, Usopp (Weak Trio)
I think it will be made clear sooner or later that the odd one out is Zoro. He is not on Luffys level but he isn't either on monster trio level. A Vice Captain, an inbetweener that is above Yonko commanders. Rayleigh and Ben Beckman are the two we know of on this level. I'd say Oden on Whitebeards ship held the same status (little brother instead of son).
You might argue Sabo is supposed to reach this level in RA with Kuzan (?), Ivankov and Kuma as monster trio and then the rest of the commanders below. Vergo as well (partner), with Pica, Trebol and Diamante as commanders.
The strongest of the monster trio (Sanji, Lucky Roux, Marco, "Kuzan", Pica) are all relatively close to the Vice Captain but ultimately there are levels.