I'm curious what the benefits are of paying for SSL certificates vs using a free provider such as letsencrypt.

What exactly are you trusting a cert provider with and what are the security implications? What attack vectors do you open yourself up to when trusting a certificate authority with your websites' certificates?

In what way could it benefit security and/or privacy to utilize a paid service?

And finally, which paid SSL providers are considered trustworthy?

I know Digicert is a big player, but their prices are insane. Comodo seems like a good affordable option, but is it a trustworthy company?