@.access:
I am not saying he is weaker than Zoro, I am saying Oda doesn't depicts him as part of the "Trio" anymore.
It's offtopic, so:
! Everytime he puts Luffy and Zoro into the scene he always make clear how damn strong they are and they are usually put side-to-side.
The same is not done with Sanji. Although he probably is at their level, Oda simply doesn't enphasyzes on his strength as he does with the other two. We know he is strong 'cause we know it, not because Oda hypes him every time as with Zoro and Luffy (he is also not seeing in scenes with Luffy and Zoro alone as a trio. You can see him with Zoro or the whole group, not the trio… Oda is not trying to make them look like one).
! While Luffy and Zoro get serious and put a face of the stronger guys in the place, Sanji at best is shown as the smart guy if not as pure comic relief. He never gets the second strongest enemy - that's only for Zoro -, just the third or some comic character (Absalom?) or nothing at all (Upper Yard?).
! Oda sees Sanji is Mr. Prince: the guy who will outsmart you and kick your ass whithout getting a speckle of dirt on his clothes.
Luffy and Zoro not. Oda treat them as pure monsters. They never pass an arc without engaging into major kickass fights that will push them over their limits or something like that. You just need to read the chapters, look at the images and you will see Oda puts them under a clompletely different light.
! I mean, damn, who are among the Supernova? The three of them? No! It's just Luffy and Zoro. In everyway, Zoro is always there, as his right-arm man. But Sanji is never depicted as the third part of this group, as a left-arm (if Oda places someone here, it is Usopp... yeah, not a monster at all).
! It's not a matter of Sanji being as strong as them ('cause I think he is), what I am saying is that Oda doesn't see them as a trio. There is no "Monster Trio" except for us fans, so let's not think Oda will write the story takin the "Trio" into account. It's a "Monster Duo"... even though there is a third monster in the group
If we're talking left arm, Nami is usually the one holding the hat…
Otherwise... I think Smoker and Tashigi should be nakama. I'll figure out the justification somewhere along the line...