My brushes are the superlite ones, cheap, cheerful, extremely light and last about 3 or 4 months before the bristles start to come out.
They hold their shape well in use too.
I've also used the Salmon brushes, found them fine too, but think the bristles (at least on the ones I had) are too short.
They are more robust than the superlite, but are also heavier and it's easier to damage window frames with the plastic brush head too.
Ian