I thought I would do a quick comparison of the watercolor brush in three of my favorite art apps: Paper, ArtRage and Procreate. They are all a bit different, and all wonderful.
Paper watercolor brush creates a stylized edge. You cannot change its size, but can control the opacity by painting slower. It also has great color blending.
ArtRage is a good attempt at simulating the real thing and does a wonderful job of it. Lots of options available in this app.
Procreate also has a stylized edge on its watercolor brush, you can adjust size and opacity as well (like the rest of its tools).
All great apps, buy all three and a Sensu Brush as well!