SL duel trim is best all rounder, six months is about right, 3 months work, spin 180 3 months then replace.
Haven't used the latest from water genie or wcw but even if the bristles haven't curled up all fallen out after a few months any bristle has lost a lot of scrubbing power as the ends have been dulled.
Vikan stop heavy
Tecbuk - unless you have a death light touch only last 2 to 3 months
Pro brush - again too heavy
Ionics - pricey, didn't find it any better than gardiners
Unger - well er... Very poor
Brodex - as above
Darran