Jordan would be my pick for these reasons:
(1) High scoring numbers (2) high efficiency (3) self-creator from anywhere on the floor unlike many post-up bigs who required guards to get them the ball in good spots (4) did it on the biggest stages - clutch situations, playoffs and finals (5) exceptional scoring numbers as both a rookie and as a 40 year old on mediocre teams. Extremely consistent.
Honourable mentions
Kevin Durant - Durant should have been the #1 scorer ever but he never made that final leap. His elite skill level in terms of shot creation, shooting ability and physical talent should have made him the #1 scorer ever. Lacked the mental fortitude of an MJ though.
Kareem Abdul-Jabbar - incredible combination of both productivity and efficiency throughout his career. Incredible consistency. As a post up big, required his guards to get in the ball in good spots so he had more reliance on others than a Michael Jordan did.
Wilt Chamberlain - would have been even more dominant if he played in the modern NBA (1979 onwards). Especially in the 90s onwards. As Wilt says - the refs let Shaq get away with murder on offensive post ups. I wasn't allowed to do those things. Those were called as a charges in my day (and rightly so). More skillful than Shaq. More athletic than Shaq.
Shaq - a man whose offensive game was defined by creating the most valuable shots in the game - high percentage shots at the basket and FTs. Unstoppable offensive game. Aggressive assertive mentality (unlike Wilt who changed halfway through his career to pass more). Utilized his physical talents well and often. Performed on the biggest stage. Dominated the league like few others as a scorer-first center in the early 00s.
Hakeem Olajuwon - A notch below some of the others. Scoring versatility gets him the honourable mention. He was unstoppable. Any type of individual defender. Any type of team defense. Did not matter. He was the man of a thousand moves. He could score against anybody. But he lacked the high scoring efficiency of the other names mentioned.
LeBron James - incredible efficiency because of his ability to create high percentage shots around the basket. He did so better than any other non-center ever to play. That gave him a consistency throughout his career that many other perimeter scorers struggled to match (their point totals game to game more variable, more up and down). His ball-handling and physical talent allowed him to get his own offense from anywhere.
Next level down I'd rate guys like Bird, Dirk, West, Kobe, Oscar and whoever else I forgot to mention.