Lots of good options out there these days and constantly more coming.
AirDev’s ‘Canvas’ is pretty good to get some functionality and have the option to buy add ons, but it can take a little bit to learn how it works and it’s landing page is slow to load as it is data driven.
My bias suggestions (made by myself):
A free well designed landing page template: Free Landing Page with Modern UI 🥳
A paid template with Login, Dashboard and Invoicing: Re-Launched Template: Dashboard & Invoicing 🎉