Eh, I can't take the Master seriously as an enemy. His cult, his Super Mutant army, and plans to turn everyone into monsters to survive the Wasteland just feel a little too crazy compared to the more down-to-Earth Enclave. I never quite understood why he was so popular except for the fact you could talk him down.
Their plan is beyond turning everyone into "monsters." You've obviously not got the entire idea of The Master down. To The Master and the Supermutants, they aren't monsters. They are the next step in humanity's evolution if we want to survive. Richard Grey was turned into the Master and it gave him opportunity to create new mutants, ones he had mental influence over. If he can control a perfect breed to never be violent once he wipes out the violent ones (humans), then he can achieve world peace with an intelligent and powerful race.
There's faults in the plans though. That's the great part. You don't just talk him down, you show him that while he's aiming for a benevolent world, his vision will not be achieved. There are two struggles, one Richard is familiar with and one he is not. One of them is that many Supermutants he's creating aren't as intelligent enough and even lacking compared to most humans. Some of them are of course and he's looking for the right formula to make them more intelligent overall. The other, he seems to not know about until you learn about it (you can't just bullshit this information) and tell him. That is that the Supermutants cannot reproduce without constantly dipping humans in vats of FEV. They cannot sexually reproduce. And when he's learned that his plan is a failure, he regrets the things he's done. He sees that all the horrors and acts of evil he's done in the name of a greater good are in vain. There's nothing he's doing to help anyone. He's not helping humans and he's not helping Supermutants.
He knows he's committing atrocious acts against humanity but he believes it's for a greater good and it's an arguable side. One that doesn't feel like it's evil for the sake of being evil nor does it feel completely misinformed. And when he's shown he's misinformed he admits it and gives up.
That's why The Master is a good villain. Sure it's that Wasteland horror trope but it's not so bland with it either. There's a scientist in Fallout 2 you can convince of something similar but the leaders still won't ever be shown this vision and Horrigan is literally just a hulking mutant that doesn't even know he's a mutant. He's an iconic villain don't get me wrong but he's got nothing on the Master. Horrigan and his leaders will always believe that radiated humans are mutants that need to be annihilated, there's no possible way they could be wrong or inferior to these "mutants."
I appreciate Fallout 1 and 2 a lot but from an artistic and design standpoint, Fallout 1 will always take the cake. It's a major theme of how does humanity go forward after a worldwide atomic crisis? Does humanity as it currently is even deserve a second chance? Should it be changed, forcibly or not? That's a big question. Do we deserve to survive after what we've done? The game reinforces this throughout at points too. The Brotherhood want to keep dangerous technology from humans that could cause atomic annihilation again. That's, in a way, a very similar idea. We've obviously messed up and why should we, as a race, be trusted again?
Maybe no one else sees it like that. But when I played Fallout 1, that's the big theme I got. There were others, sure, but that was the major point driven home to me. The Glow was a big part of that too. Someone jokingly told me to go to a relic, a graveyard, of our former world. A place void of life, a pit in the ground. A sinkhole full of despair.
