Bronze Forever has the biggest server, most gen 9 pokemon of out all copies, and almost no bugs, Bronze Odyssey has Kyogre, Groudon, and elite 4, Grand Obsidian has Dynamax and Gigantamax, Shining Silver just a really good copy of the og pbb
I suggest to play Project Bronze Forever bcz Bronze odyssey has some bugs, Grand Obsidian is wayyyyyyy too hard for someone to complete and Shining Silver isn't as good as PBF