I have been using DocRaptor for 6 years, both for my professionnal and personnal projects. After trying several free and/or open source HTML to PDF solutions, I was happy to find this service. It's the most efficient solution, which generates the most accurate PDF documents.
Since it's a SaaS service, there is nothing to install, no library dependencies nor experimental software that you're not sure it will be supported in the future.
There is a lot of options and CSS rules to dig in if you want to get PDF files that exactly matches what you want. But the other solutions I tried didn't have these options, and the result was not good enough.