My recommendation is to look beyond the free alternatives and consider how inexpensive paid certificates have become. These can be issued for lengths up to three full years and cost well under $10USD/year. Multi-year discounts bring three year certificates price to under $20USD.
Think about how much time it is going to take you to learn how to deploy and maintain your 'free' certificates and remember time is money. What do you make an hour? Is that more than the cost of a paid certificate?
Don't waste hours chasing down free certificates when paid ones are so cheap now. Use Let's Encrypt only if you need lots of certificates and the paid options become prohibitively high.
Think about how much time it is going to take you to learn how to deploy and maintain your 'free' certificates and remember time is money. What do you make an hour? Is that more than the cost of a paid certificate?
I have used these certificates - https://cheapsslsecurity.com/comodo/positivessl.html - on multiple sites and it is very fast and easy. Other vendors sell them too and are likely just as good. Gandi do them too (at a slightly higher cost) and are the fastest method for me, though this may be because I have all my domains there already: https://www.gandi.net/ssl/standard?currency=USD#single
Don't waste hours chasing down free certificates when paid ones are so cheap now. Use Let's Encrypt only if you need lots of certificates and the paid options become prohibitively high.