Ibra has been very good with the Swedish NT. Has he been stronger than Messi/Ronaldo have been for their NT? About the same I would say. But the difference is that he stands out so much from the rest of the Swedish NT that he just seems stronger for some.
But really, we should stop comparing these 3. Ibra has been a top 10 forward for the last 10 years. Ronaldo has been the second best of his generation. Messi is the best player that ever played the game, ever - no butthurt-ego-Pele, no Maradon, no nobody - only Messi.
Hmmm,Zlatan has only played in 2 world cups .2002 & 2006 .in first he has came as a late sub twice,while in the second he has played 2 and half games scoring zero goals .an amazing World Cups he truly had
He had relatively better Euro Career ,scoring twice in 2004,2012 and once in 2008 .but only qualified out of the group stage once in 2004
So While Zlatan is amazing player for Sweden no doubt .you can't put his international career on bar with the likes of Cr7 & Messi when it is all in qualifications and group stage
Messi has 2 quarter finals and one final appearance in the world cup and in two of those tournament he was clearly his NT best player .Cr7 has played with portuguese team that had reached final,SF&QF in Euro .also was a part of the team that reached SF in WC 2006
Those guys simply played against tougher opponents and was amazing for their NT .I would still put them over Zlatan in terms of international career