I use Reaper 6 in all of my tutorials. It’s a powerful, stable and highly configurable DAW with an extensive feature set. The audio quality is the same as Ableton Live, FL Studio, Logic Pro X, Cubase etc. It also performs well on old hardware with limited resources.
You can download a free, fully functional 60-day evaluation of Reaper without creating an account. After the trial period, you will need to purchase a license for either personal or commercial use.