Notes on the installation of Drupal 7 running on CentOS7 using Nginx and SSL certificate from LetsEncypt.
This is based on my experience installing on a VPS.
The VPS came pre-configured with Apache running. (The VPS also had Parallels Virtual Automation)
Nginx was chosen as the server was for a very specific use-case; running an event entry/management system. Entries to the event in question open once a year at a specific time and because places are very limited, the server experiences very high load immediately, for about 10 minutes, whilst all places are booked. The number of concurrent connections during this time is extremely high. To run with Apache would require massive amounts of RAM and very careful Apache config. Nginx reportedly handles this scenario much better with much simpler configuration.
NOTE: At the time of writing, this is yet to be proven.
CentOS was chosen as a robust server distribution. I'm familiar with Fedora/RH, so am comfortable with CentOS.