Say you have a team of 4. 1 junior, 2 mid-level and 1 senior.
The senior engineer can get the story completed quickly (say 1 point). For the junior, the work is more complicated; he/she doesn't know the platform as well and the expectation is that it will take 3 points for him/her.
The mid-level people can complete the story in 2 points.
The team average is 2 points for the same story.
Do you assign story points based on the assignee or based on team average?