Toronto house painters very frequently use Purdy paint brushes. These paintbrushes are a professional quality. When using these brushes you will find that they hold a lot of paint and retain a straight crisp wet edge as you glide along the wall cutting in the ceiling.
These paintbrushes maintain a good quality condition for long. Time provided that they are cleaned properly. Paint brush maintenance starts in your hand. The less dirty you get the brush with paint the less you have to clean off the paint at the end.
To clean these paintbrushes the best way is to soak them under running water until there is no more milky water coming out of the brush. When you are getting finally a very clear drain out of the brush then your brush will be good for the next time.
Here is a quick video on handling a latex paint brush: