Xavi's profile was incredibly rare and unmatched in CM.
Counts against his teammates that as soon as he declined and disappeared from Spain NT, the team irremediably declined with him. Even though many of Spain's younger top class players were still around, including Iniesta, Busi, Sergio Ramos, Pique, Carvajal, David Silva. All big talents, most legends themselves, but neither could fill in the gap of losing Xavi. Other Spanish creative midfielders edged towards a no10 or a no8. Neither was the full package in one like Xavi.
Iniesta was pure class and style though, with big attacking moments in clutch situations, even though he was not a big scorer usually. Similar to a Zidane, or even Modric and Pirlo.
But if you could choose one player... that is Xavi in midfield. More influential overall from first minute to minute 95. Defense benefits hugely from it too, not just the attack.