James
Asking which brush to use, is like being in a nightclub and asking 'which girl do you fancy'?
Or being on Autotrader and saying which car do you like?
You are going to get 10 different answers.
And that is exactly how it is!
You need to decide, what YOU want in a brush and pick the one (or two that suits you).
For me, I have dodgy elbows, quite painful, so I need the lightest brushes possible; the Xtreme
They basically have the stiff, (which I use mostly) and the natural bristle, (which scrubs the glass better, but drags across the glass), this 'dragging', motion, cleans better but takes longer and asserts more effort. Not good for me!
For leaded I use an old Xtreme flocked (which they don't make anymore). It is totally knackered, but moves across (even square lead) like it isn't there. I also have another flocked (never been used), that I found in my garage, that I use for fsg cleaning as it is so light. I put fan jets on that one too.
As an everyday brush, the Ultimate medium (orange and red, I think) is hard to beat and for leaded the new superlite flocked is amazing.
Although I have all the brushes mentioned above, I stick with the Xtremes.