It's the third one, guys. I'm literally the only one here save that Spanish guy that knows this for sure. Argentineans and Uruguayans do use a "sh" sound, but that isn't the typical pronunciation. Plug the word into Google translate in Spanish and see for yourself.
What is the typical Spanish pronunciation of tortilla?
Eagle

ask @__ for secondhand opinion
i can confirm that this bald entity is wrong and its the 2nd one not third