A portal to another world opens in front of you. You don’t know how long it will stay open or if you’ll be able to get back after you go through. What do you do?And which world would you choose ? A reminder , you might not be able to get back again !

Off the top of my head:
* SAO because of future tech
* Ready Player One
* Secret, because I'd love the chance to their smiling face in person.
As for if I'm not able to get back... who cares... I'm not leaving much behind here.