So the only common point for everyone here : second strongest
No, the only common point for everyone here is that they are all the No.2 or one of the No.2s in the crew in terms of overall importance or authority.
According to the text provided by Etenboby, Oda literally wrote that they are just the No.2s that he picked out; Oda is not specifying why he picked out each one of them.
The person who was asking the question to Oda wasn't just asking whether or not Bepo was the No.2; The person made two questions, and the second one was about whether or not Bepo is the strongest out of them.
So first Oda answered the first question, clarifying that Bepo wasn't the only No.2, just like Zoro is not the only No. 2.
And then he proceeded to answer the second, which was about Bepo's strength itself, so Oda wasn't even talking about his strength as a justification for the choice; Those were two different matters.
This is how Oda could have written the text if he really wanted to confirm that Zoro is stronger:
Oda: talking about that color spread huh. Same goes for Zoro, not everyone on there holds the position of vice captain. They are just the No.2s that I picked out
based on strength. Penguin and Shachi are more reliable in normal circumstances, but those two have seen Bepo's sulong transformation, so they acknowledge that "combat wise Bepo is superior!",
just like combat wise Zoro is superior to Sanji.
But Oda didn't do that, which wouldn't have been so hard to do if he really meant to convey such message.
By the way, it's not even confirmed that Shiryuu is stronger than Jesus Burgess, especially considering how Jesus Burgess was chosen by Black Beard to be the captain of the first ship.
And if you want to argue that the difference of position is not enough reason to think that Burgess is stronger than Shiryuu, then you also have to accept the argument that Jozu may be stronger than Marco.