Rest api or direct database? Ajax or curl?

What I want is to display data from mysql database based on inputs from form. The website is live at http://condense.press/ Which of the following is a good architecture.
1) Directly interaction with database and displaying in iframe. This one is currently used at the master branch.
2) Directly interaction with database and displaying with ajax. This is done at https://github.com/agnelvishal/Condense.press/pull/22
3) Using curl to call rest api which interacts with database. This is done at https://github.com/agnelvishal/Condense.press/pull/24
4) Using ajax and rest api.
5) Using frontend frameworks like vue or angular.
Expecting answers from #Hacktoberfest