Avoid those Testors plastic fibre thingies at all costs. The bristles are MUCH too stiff, like using a toothbrush to paint your model.
Red sable is probably an overkill, but nice if you have money to burn. Or if someone gives them to you..
There are perfectly serviceable synthetic brushes available for $5-8 AUS (each) that will last several years if cared for well and - most importantly - won't shed hairs.
Some hobby shops have good ones. Art supply stores will often be cheaper for the same brush.
Brands I have on my bench now are Humbrol, Delta Nylon, and A.J.Leeman Hobbies Synthetik.