Will be following this as I'm in a very similar situation - To give you a perspective from what happened to me from my choices I'll share what I did and what happenedmy story:
My "bully" wasn't an experienced senior, it was the opposite, someone almost half my age a few years out of uni in his first real job who thinks he knows everything. To be fair he is a great engineer but a lousy teammate.
I quietly wrote everything down for months, had a record of everything, what was said, who was present, date/time etc.
Then I chose to raise the issue with our line manager and have called out the actions of the person doing the bullying. I told them of my records but never shared it but did say I will take it to HR if needed and that will be a lose/lose for us all (as we all know: HR is not your friendHR is not your friend). It
It has since resulted in an in team mediation but the bullying party is still arguing back even to the manager that he is right and he isnt nitpicking. Overall I feel it has been very damaging to my career and in hindsight I should have just quietly looked to move to a different team with a different excuse (which I am doing anyway) instead of making an issue about it. However I didnt want to let it go without the bully being called out on his actions. He
He has (so far) stopped bullying - in fact he wont come anywhere near me. It is an ongoing situation.