Im vouching for Jazz, he did some pretty good work on Undeadland, tho right now the island isn’t super active as I am waiting for mostly arch side to finish builds. He also helped out a lot on captain island. I really don’t find managing multiple islands very conflicting since Jazz doesn’t really look for builders for me so I highly doubt there would be conflict. What I can assure you is he gets things done as long as you give the order, he will try his best. I was on a trip and he unregioned plots that I wasn’t even sure that I could buy back but he pushed to get them back from the plot owners etc....
I myself wouldn’nt mind him working for gamerboy because I know he actually has the time and skill to multi task and manage. So yeah lava, would highly recommend him, I think another problem faced is that you might think your managers would look for the cheapest arch so they can make a lot but Jazz isn’t the greedy type. I think I had about 4-5mil overdue fees I had not payed him for his work yet he didn’t request a single dollar till I remembered to pay him the money he earned.
So very high hopes for Jazz he has worked also for Runnerboro in the past so he was able to go through different lines of management.
I would also recommend seb, because he has lots of connections to Architects however I am in no position to fuly judge anything he has done. Tho he has worked alongside me as a gangmember and has been very passionate and dedicated to the things he wants done. One example would be nekokingdom, right after he got the plot he immediately got an arch working to complete it.
I feel like seb is better at finding connections wise, however I feel like Jazz is more on the technical side, he will pinpoint your mistakes and make sure its fixed. They both bring a great sense of dedication for the job, tho its probably best if you hire them both and just make them split the earnings from the project since they bring different sets of strengths and weaknesses which they can better hone and apply to help finish your island.
Overall, these are based on personal views I had so please no hate. I wish the best of luck to both of you and I see great potential in you both.