Long ago Mr. Lindbeck kept tagging the glass as he tried to get into the corners of the window mullions, he considered the problem and with the help of a pair of scissors the angle sash brush was born. I do find them useful when painting window sashes and not much else... but I am also aware that a straight cut brush is not intended for extended edge use (painting with the brush turned edgewise ) after a while the bent bristles become compressed, develop a memory, and take on a semi-permanent curve which can make it useless when you run into some flat work....
If you could have ONLY ONE brush what would it be, angle or straight cut?