What is the best landing page builder ?

landen.co

+1 for Lenden and Carrd

Adding Brizy, Leadpages and Tilda to the hall

Another vote for Landen.co here! The founder is also an Indie Hacker member

Sorry to out of topic, but I found this guide was very helpful https://sumit.versoly.com

carrd.co 👍

If you need to build a personal landing page, you can use https://oneprofile.info

If you need to build a landing page for your projects, teams, and brands, you can use https://oneprofile.team

While it isn't a web app, Divi theme for Wordpress has worked great for me.