There are more reasons, as LetsEncrypt might be more restrictive on what you can get (for example, you cant get a certificate for an IP address from them). But, as 99.99% of usecases do not require anything like that, go with letsencrypt until you know of a reason not to.
I see why automatically giving them out (like in ACME) would be a bad idea, but other than that, why not? Even https://1.1.1.1 has a DigiCert cert.