Iniesta is good, but I think Modric is better - just he is not praised as much in public as Iniesta is, because his career started to track attention since he joined RM, which is 6 years ago. While Iniesta played for Barca since 2002 and Barca was also in media.
Iniesta has perhaps better ball control and some interesting way to find good passes to FW, but what makes Modric shine (IMO) is how passionate he is to help the team, try to take the ball from opponent and how well he manages to keep the ball in his possession + his incredible stamina, running / sprinting also in 100+ minutes.
I think comparison between Modric and Iniesta is in good place to be honest, similar style players. But Spain did not make much in WC, so I agree, if Croatia by any chance win WC, Modric has good chance for Ballon d'Or.