It is really hard to choose a favorite brush, if you use several different types of paint or media, work in a range of sizes, or just like art materials (like me). But, if I had to choose a favorite for my heavy body work, it would be the Dynasty Golden Stag Brushes -- hands down. Mostly, this brush is incredibly comfortable with a sharp edge. I couldn't ask for anything more.
This is a synthetic brush, with the feel of a dense bristle brush yet stronger. It is built to withstand hours at the easel and hold its spring and edge for years. Incredibly comfortable handle and a double crimped ferrule for balance. Since these are synthetic, they hold up well on canvas and rougher painting surfaces, like stone or wood. Available in round, filbert, flat and bright in a variety of sizes and sets. You can find these lovely brushes where Dynasty brushes are sold: dynastybrush.com/dynasty_distributors
For more brush information, check out the Dynasty Brush website.