Likely not Gaban.
If Roger wanted to hide the 4th Poneglyph like that, Rayleigh could've done it. It doesnt make sense to me that Ray is chilling in Sabaody while Gaban is busy on a ship hiding a Poneglyph.
Also Oda loves his patterns, he introduced Roger in ch. 1, Rayleigh in ch. 500. So if he wanted to bring Gaban into the story, he would've done it around ch. 1000.
If Roger wanted to hide the 4th Poneglyph like that, Rayleigh could've done it. It doesnt make sense to me that Ray is chilling in Sabaody while Gaban is busy on a ship hiding a Poneglyph.
Also Oda loves his patterns, he introduced Roger in ch. 1, Rayleigh in ch. 500. So if he wanted to bring Gaban into the story, he would've done it around ch. 1000.
Even with the characters they parallel, Zoro and Sanji, Zoro will be the one known as the WSS and RHM to the Pirate King, while Sanji... He'll have his title Ig. Idk what they'll be but he'll have them.
Anyway it's probably Dragon. Possibly Gaban.