I love Steel so much.
Objectively speaking, of course it's very strong and has the best defense. I find it amazing that "technology" in general would be considered an elemental type of its own.
But within that type there's still a great deal of diversity. There is mawile, lucario, empoleon, a-sandshrews and whatnot. And that's not talking about my favorite legendary; I want to hug whoever decided Time would be represented by Steel.
https://youtu.be/XgiDQa0zSi4It's so perfect.