We continuously compare M.J. and LeBron despite the fact they never played against each other. The only thing you can find out from such a discussion is the personal preference of the people involved. A much more interesting debate is between two players from the same era, players that defined the last decade of NBA basketball. Wardell Stephen Curry II and LeBron Raymone James Sr.
If you are subscribed to NBA podcasts and news outlets, you have heard by now that as much as Steph was the most popular player of the past four years, most NBA stars still put a lot of players ahead of him. Just pay attention to how Chris Paul or Russell Westbrook look and act when playing against him. They both believe they are better players than he is (they are not) and always make a point to play physical with him. While still an executive with the Warriors, Jerry West talked about the difference between Steph and LeBron in an interview:
He plays the game with no force. LeBron James, James Harden, all of these guys play the game where they play with force. He doesn't, and he's still the best player on a team with the best record. He's clever; he's not going to overpower you with strength. We have the most fun team in the league to watch, and he's a big part of that.
It's a machismo thing. They are tough, strong, fast; they are physical in the way they play. Steph looks skinny next to them, and most of the time, he avoids contact. His is a game of skill and finesse, not strength. Curry profoundly redefined the game, and most of his competitors can't out-do him. It's a microcosm of the generation clash happening before our eyes. The "back in my day" argument, only on the court.
They spend their whole life carrying a chip on their shoulder, being tough and aggressive, and now a happy-go-lucky skinny guy shows up, throws up a lot of shots, and suddenly he is "the guy"? Imagine being the best film photographer around, and then one day, someone shows up with a digital camera. Well, screw that person and, by the way, they aren't better than you – they have a digital camera that Steph's peers don't understand that it is tough to be the first guy with a digital camera. That means you've been working on it while everyone was doing things the way it's been done for years.
Then there's the whole "basketball royalty" part. Unlike most of the players, Curry had a privileged life. Not only did his family have money, but his father was a good NBA player, so Steph had access to the league and the game in a privileged environment from a young age. He didn't go through the life Westbrook or LeBron did, so he can't be as tough as them.
While it is true that growing up in a family with financial stability makes life more comfortable, it does not necessarily mean you are "soft."
The last part of it is something I do not have a connection with, so just a short mention. There is a "light-skinned" narrative to Steph (and Klay for that matter) that influences their standing. In an article for The Conversation, prof. Ronald Hall writes about the historical relevance of this phenomenon and mentions how Kobe once told Jordan Clarkson to "go to the hole like a dark-skinned dude." Also, check out the piece Michael Erik Dyson wrote for The Undefeated.
P.S. Muscle size doesn't necessarily correlate with strength. After his ankle injuries, Steph had to reinvent the way he runs, shoot, the whole shebang. In the process, he developed his core and leg strength so much he is at the top of most metrics on the Warriors.