A rigger brush is specialized for lines - a "medium round (the pointy but wide-ish one)" is not, and will most definitely frustrate a beginner who is trying to

A rigger brush is specialized for lines - a "medium round (the pointy but wide-ish one)" is not, and will most definitely frustrate a beginner who is trying to do good consistent line work. The first rule for choosing a brush should be to choose the correct one for the job. Sure, an experienced artist will have better brush control, but this guide is for beginners.