Jordan is more popular, because in the mid 90s we didn't have internet forums overanalyzing his advanced stats and a cynical mob tearing apart every interview and every aspect of his personal life. There was jealousy when Jordan was around as well, but we didn't have global hubs to seethe together. You'll never see another Jordan (in terms of popularity) for the same reason you'll never see a globally beloved band or musician like the Beatles or Michael Jackson. Different era. Too many options for one thing to hold our focus. We saw the "Be Like Mike" commercials. We all digested the universal praise heaped on him. We were on board with movies like Space Jam... and we all bought into the idea that he was a superhuman force of nature. We didn't have forums for ceaselessly debating the "weak competition" Jordan was facing off against (Post Bird/Magic), how the league was letting him get away with murder nightly, or how the league was literally changing rules to match Jordan's skillset (like when they moved in the 3 point line for him). We didn't have endless internet debates about Scottie Pippen's impact in relation to Jordan and how Pippen's two-way game was the true leader of the team (55 wins without Jordan) ala debates claiming D-Wade was the best player on the Heat. It definitely helped that he was the greatest basketball player of all time and probably the greatest athlete of our generation. It didn't hurt that some of us were children at the time... I remember watching the Michael Jordan cartoon and never once did I think, "Dude needs to focus on basketball instead of pimping his brand everywhere".
If LeBron played in the 90s era, he'd be just as beloved.
If LeBron played in the 80s era (where fictional athletes like Hulk Hogan had legions of followers and Bird/Magic was an unchecked spectacle that carried the league), he'd be glorified as well.
But LeBron plays in 2015... and every step he makes gets overly scrutinized. When you cut through the bs, you start to realize he's one of the greatest athletes ever playing at peak level. He's accomplishing extraordinary things. And for kids growing up today, LeBron might be the closest they will ever have to Ali/Tyson/Jordan.