Iff we talking about numbers...eh...you can't go wrong...they both do VASTLY different things but you can make the argument that they are the absolute best at what they do...
If we are talking about all the other basketball stuff it's Duncan and it's not even close...
Bron has 3 rings...Timmy won 5 rings across 3 decades...
Timmy won a title when the spurs played at the slowest pace in the league and he had to do everything...he won a title when they played at one of the fastest paces in the league and had one of the highest points per 1000 possession ever during that 2014 playoff run...Lebron had to attend Paat Rileys "how to win championships for dummies" seminars to win a ring...
Timmy won with guys picked at the end of the first round (Parker)...goes picked at the end of the draft (Parker)...guys who were in the d league and out of the league period (Green)... Lebron HAS to have at least two other lottery picks on his team to get to a championship level (wade and bosh...kyrie and love)
And most importantly...you can build any type of team around Timmy and win...Need him to come in and help your aging big man as a young player...he did that...need him to carry the team and win while a 19 year old point guard learns how to shoot a basketball...he did that...when he gets older and you want to preserve his career can you give the offensive reigns to the point guard who still can't shoot and a euro who was picked 57th overall and still win a title...he did that...you need to play at a break neck pace and need Timmy to focus on rebounding and defense...while you groom your next franchise player who can't do anything but rrun fast jump high and play defense...no problem he can do that and it will be one of the greatest offenses ever...then just for shyts and giggles after your next franchise player becomes your franchise player damn near 40 year old TImmy can anchor one of the greatest defenses ever...
Lebron

...dude is the opposite of this...you don't put lebron on a team and make it work...you have to build the team around Lebron...and you have to build the team the exact same way...you need a minimum of two guys making max or near max money and you need enough shooters on your team to put 4 of them on the floor with him at once...
You draft Timmy you can put virtually any type of team around him and not only win a lot but win multiple championships...you draft lebron...you better have two other guys who are making at least 50% of your cap otherwise the first chance he get he is "taking his talents" somewhere else...