Manufacturing companies, particularly those that mass-produce electronic circuits, work pretty much around bipolar junction transistors, like PNP and NPN. However, choosing between these two BJTs ...

He does explain why PNP transistors don’t perform as well as corresponding NPN transistors, but they are still necessary sometimes. Once you get used to it, they are no problem to handle at all.

The transistors used (a 2N3055 npn and 2N2955 pnp in TO-220 packages) are reasonably good choices. They should be placed on a heat sink for good heat dissipation.