As a PC, I’d rather face five opponents than one. And, as the DM, I’d rather throw five opponents against the PCs than just one. This has been my take on combat since my earliest days of D&D. As new editions of D&D got released I kept an open mind and explored the possibilities again, but every time I found the outcome the same. It’s better to have the PCs fight a mob rather than one really tough foe.
I’ve encountered very few gamers (DMs or players) who disagree with me on this point. The number one reason I’ve heard is that it’s boring to fight just one monster no matter how powerful it is. So if no one wants to fight just one monster then it sounds to me like something’s not right with the game. And if that’s the case perhaps we can do something to change that. Let’s figure out a way to make fighting one really tough opponent as much fun as fighting five guys.