Ask HN: How to decide which idea to build into an app

I currently have a few app ideas and am unsure which one is likely to be more commercially successful.

I would like to do some initial validation and use a quantifiable metric to determine which app to build out an MVP for.

I was considering making a landing page for each idea and then using Facebook ads to drive traffic and then building out the idea with the most sign ups.

Does anyone else have any processes they use to compare app ideas and get hard data on which idea to build into a product?