Put on an exciting Staff level project for the last 6 months. Now, asked to make a tough choice - move out of Org or stay in current Org and give up scope.
Pros of moving:
Cons of moving:
TLDR; What would others in the same situation recommend? From taro courses, Option 1 seems better. But there are unknowns especially with current manager refusing the offer.
It feels like going to the other org is better. You have 6 months of signal working there, so I'm sure you have a good handle on the quality of its team and scope. When going from senior to staff, you need to be very particular about the team you work on: https://www.jointaro.com/course/grow-from-senior-to-staff-engineer-l5-to-l6/finding-the-right-team/
It does suck that your manager seems to be unsupportive of the move though. In general, manager relationships are very valuable, so hopefully you can maintain it and not burn any bridges. Here's a good thread about this: "How can I gracefully leave my job?"
Best of luck!