i mainly use supreme brushes for lots of work these days.i think they are a good balance between SL and extreme.however on some runs of work(4 days worth) an extreme brush makes things a lot easier due to lots of awkward angle windows on nearly every property.standard SL brushes still get used for very dirty first cleans and large accounts with big windows,sill brushes for f/s/g and conny roofs.
the other week i saw 2 employees of another window cleaning company struggling to clean the windows over a kitchen extension with aluminium poles and vikan sill brushes!been there ,done that!vikan brushes might last forever but their joints and elbows wont.
alex has a staggering range of different brushes to cater for various applications.
ive just received a supreme medium hybrid i ordered and will be trying it out today.this could become my favourite brush!(for now!)

SL standard brushes most hardwearing brushes alex does IMO
supreme brushes lighter than a SL.good all arounder.
extreme brushes ultimate lightweight brush for awkward angle windows and high level windows
sill brushes i find them great for f/s/g and conny roof cleaning.
the extreme brushes in particular dont last long if used all day every day.a few months say but the sill and SL brushes will last ages.