Will always be an interesting hypothetical to wonder what he would've looked like in the NBA. Probably something along the lines of Manu's career. Can't blame him for choosing a great life at home over making more money and playing with the world's best in the NBA, I would probably do the same in his shoes--he's one of the GOATs over there and life's gotta be good. But it would've been cool to see him in the NBA.
Being a spaniard myself, I have to admit that Manu was much better than Llull. A couple of better comparisons would be Calderon and Ricky Rubio. His NBA career would have been in that range.
Juan Carlos Navarro was a great player, and probably more similar to Llull than the other 2, but he played only one year in the NBA. In FIBA basketball he is a legend. I compared Llull to the other 2 as most USA fans will know them better