I have used many ranges of brushes, starting with the original Tucker brushes, Unger, Gardiner brushes, Ova and there are many pros and cons to all of them.
My favourite choice is the Reach-It brushes for a couple reasons. It's not because of the weight as they are heavier in general. The main reason is because the bristles retain their shape very well and don't fall out for example catching on the hinges and plastic trims on UPVC windows. The most important reason I use their brushes is because I can use a greater flow of water which produces a higher amount of water along the top of the bristles which are so compact that it acts like a blade preventing the water from running between the bristles and also runs around the outside edge of the curvature of bristles which makes a massive difference to the water sheeting on the glass as it cascades down the panes, so even hydrophobic glass is much easier to clean without spotting after drying. I prefer to use their lightest brushes with inside bristles or pads for maintenance cleans and their longer, heavier brushes which have longer bristles for initial first cleans which are best for cleaning the frames however dirty.
Gardiner range of brushes were always my go back to brush in the past, but, ever since Reach-it got their brushes near perfect I have remained with Reach-it as they have suited me perfectly.
I wish Alex the best of luck with his business and long may he continue to provide a reliable service for others.