I have tried a few different brushes none of alex's though, don't dispute his are good from what is said on here.
brushes i have tried ionics double trim, vikan flocked, peter fogwells autobrush.
The brush for me is vikan mono-filament hi-lo, great brush ticks nearly all the boxes for me,
the only thing you could say against it is it is heavier than most brush but on a light-ish pole i can't see the problem.
Good scrubbing power, stays clean, can do sills as well.
thanks lee.