How can I answer that without talking to the 16 other clubs? You also suppose he's competing with the incumbent.Which other NRL club would have him as their starting fullback ?
But to answer your question, probably St George, I think given the chance Parra would take him and punt Gutho, right now Cronulla would take him over Tracey, Titans maybe.
The question isn't if he's better than player X and replaces him - I wouldn't want to swap Bula for most of the current NRL fullbacks. The question is what level of interest there'd be if he became available and I'd say a lot.