I think the Scotland #10 shirt is wide open for the 6 Nations, regardless of whether Parks is the best 10 or not any more, the management might want to move on from him given that he's 33 now
Weir is definitely a contender now, I would give Jackson a 65% chance of starting the first 6 Nations match v England, Parks 15%, and Weir 20%, but that could all change over the coming months, to be honest I think Weir bosses the game better than Jackson currently does so I would opt for him
Phil Godman is way out of contention now, struggling to get into the Edinburgh side, and they picked Gregor Hunter ahead of him the other week against the Scarlets and Hunter was seriously awful so Godman must be out of form to be on the bench behind him