What Is The Best Travel Search API (flights, Hotels, Etc) Today?

I have a little personal project that I’d like to build and I see there are a number of APIs available around the Internet (RapidAPI, apify, etc.)

Is there a known best-in-class API that provides flight information/pricing from most airlines, can discriminate by coach/business, and offer information on hotel availability and pricing too?

A while ago I tried an API from RapidAPI, but quickly discovered that it wasn’t bringing in a lot of stuff from lesser-known airlines (Copa, smaller Euro carriers, etc). I’d like to build this on top of something solid, but that doesn’t require me to buy millions of calls a month since this is a personal project.