I prefer to choose a PaaS or SaaS that I can "easily" replace if something goes wrong (ie: they shut down)
Hosting companies? Dime a dozen. I host with Rackspace, but I could move to AWS or DigitalOcean or any number of hosting companies. Linux is Linux.
Same with the database. I am and probably always will be a huge fan of SQL. MySQL can run anywhere - again, at Rackspace, AWS, etc... Both of these (hosting and database) if all else fails, will even run on in house servers. With a little work, I don't even need MySQL - it could be MSSQL or Postgres or Oracle or ?
Some systems are out of convenience. I love Cloudinary - I haven't found a suitable alternative to it but if it went away; it just processes images and videos. It'll be a burden to not have it, but it's not mission critical.
Search? I use Algolia. Would it suck if the website doesn't have a search feature? Sure. But it won't take down the site if one day they close their doors and - with a bit of code, could be replaced. They make it easy to search and maintain the index, so I use it. But I could of very well have written some scripts to search the DB and not need another service.
Everything will come to pass eventually. Recognize your potential points of failure and have a plan or even just an idea of what you might do, if that service went away.