I'd have to qualify that as "the best free player you can't program". That's because it gives very little control for tweaking sounds, so you'll rely entirely on add-on patch libraries. By the time you've acquired all of the available libraries, you'll be down a couple hundred bucks and at this point it's no longer a free synth, but a moderately expensive one.
However, the add-on sound sets for Synthmaster are outstanding, and individually reasonably cheap.