Sanji - best at leading during espionage/side-quests
Zomo - better at leading during domestic crises within the crew
Franky - best at leading the weakhats during boss fights such as against Meme or Saturn
Jinbei - Helms Leader when he must take helm when the Sunny is under attack or needs immediate control
It was never stated officially that in manga or SBS that Zomo is vice-captain
Several of the strawhats have stepped up to fill-in for Luffy, most commonly Sanji who has had more leadership moments than any of the strawhats
Luffy has a lot of burdens on him and the captain needs more than 1 team lead, hence Jinbei and Sanji for example taking leading roles regularly in the post-TS
In term of amounts of leadership moments, Sanji > Jinbei > Franky > Zomo > Others
To support my argument, Oda himself in SBS says:



Zomo - better at leading during domestic crises within the crew
Franky - best at leading the weakhats during boss fights such as against Meme or Saturn
Jinbei - Helms Leader when he must take helm when the Sunny is under attack or needs immediate control
It was never stated officially that in manga or SBS that Zomo is vice-captain
Several of the strawhats have stepped up to fill-in for Luffy, most commonly Sanji who has had more leadership moments than any of the strawhats
Luffy has a lot of burdens on him and the captain needs more than 1 team lead, hence Jinbei and Sanji for example taking leading roles regularly in the post-TS
In term of amounts of leadership moments, Sanji > Jinbei > Franky > Zomo > Others
To support my argument, Oda himself in SBS says:
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