I use Ionic, Vikan, and Salmon brushes at the moment.
If the windows are reasonably clean and good condition, I don't find much difference in the result, sometimes the Vikan leaves spots on these.
If the windows are in need of a scrub, the Salmon or Ionics work best, but the Salmon is leaving windows a bit unfinished.
If the windows are nicely conditioned, the Salmon brush is leaving a good finish, quickest.
But, so far, the Ionics is proving to be the best, all-round brush.
Just my opinion so far. But I'm learning.