Sometimes choosing watercolor brushes can be a difficult task, especially when you are new or fairly new to watercolor. I teach watercolor painting classes and I have done quite a bit of research on various brushes, I have tested a lot of brushes. I have purchased more brushes than I care to admit. Not only are there different brands, there are different sizes, shapes, elements, etc.
For those who are new to painting and are looking for a decent economical choice, I would highly recommend Princeton Brush Set (shown in photo 1), made up of white taklon bristles (a synthetic). It has brushes size 2, 8, 12 rounds and 1/2" flat, plus a 3/4" one stroke. They are inexpensive and work very well. A step up and my favorites for watercolor class is the Winsor Newton Septre Gold Series (shown in photo 2), which are a synthetic and sable blend. This includes from left to right WN Series 965 1 1/2" wash brush, WN Series 680 3/4" one stroke brush (this one has synthetic bristles), WN Septre Gold 6, 10, 2, 4 round brushes, all make up a perfect set of brushes for watercolor painting. They hold a good deal of paint and water, have great "snap". I don't think there is a better wash brush than the WN Series 965 1 1/2" wash brush, it also has the synthetic sable blend, it is worth every penny.
My absolute all time favorite brushes that never leave my studio, for fear of loosing them are my Winsor Newton Series 7 Sable brushes (black handled brushes in photo 3). The Winsor Newton Series 7 Sable brushes are coveted brushes by watercolor painters around the world. They hold the most amount of water and paint and are simply delightful to paint with. Photo 3 shows the brushes I personally use most often. I do have another larger container that holds a lot of my other brushes, which will remain a secret for now.
As your painting skill improves ... spoil yourself with better brushes!