In this course, we will use plugdata, as it has decent audio and MIDI hardware / software support and can be used as a VST3/AU/LV2 plugin for various digital audio software systems. It also comes with several libraries installed by default that provide a wide-range of objects not available in Pd-Vanilla.
If you have used Pd before and prefer Pd-Vanilla, you can keep using that (with the understanding that you may need to access external Pd libraries). Otherwise, use plugdata.