I have all 3 of the above. If I was scrubbing something well and make sure everything is wiped off, I would say the standalone brush (at least mine) is best. The brush around my vacuum does not have the same type or density of bristles.
My personal feeling is my robot is better than the brush/vacuum attachment. I am sure there are some better ones of these available, but I bought my robot within a week of my pool being completed, and have used the vacuum/brush combo only once.
For me, the #1 is the combo of brushing with the standalone brush, then following up with the robot to sweep up. I keep the fine filter in mine, and this picks up very small (down to 60 microns). And rely on sand filter to get rest.
So to summerize:
1 - When something really dirty/stuck on - brush well then robot
2 - Normal - bush along steps and ledge, then robot
3 - Quick clean - robot
4 - Brush alone
5 - Brush/vacuum combo