Molloy also played the character on-screen a while longer, too. But with Beevers, I appreciate him as being a unique Master who on audio was built on based on the little we had of him (he's the same incarnation as Deadly Assassin and Keeper of Traken's), and I also like him the most because he's, I feel, a far better actor than Ainley was. I like Ainley at the best of times, but I can't see him performing Master with the same texture, nuance and subtlety. Beevers' velveteen voice works wonders in establishing him as a dreadful opponent but also the tragedy of the character in the story.
I do, however, wonder and can even imagine, with a bit of squint, the story with Pertwee and Delgado. Squint, as the framing story would never fit with the Third Doctor. The abstract figures of Death and Time were Virgin New Adventures takeaways, so I cant really see almost any Doctor dealing with those concepts, bar the Twelfth Doctor, ironically enough. But indeed, Delgado would have made it sing, as well IMO. Come to think of it, Jacobin would be wonderful in it, too.