All our sites are running on WordPress, the largest CMS (Content Management System) on the Internet today. We are running most of our sites in a couple of different Multisites (for our internal sites, for our external clients, for development/staging).
We are using DigitalOcean's VPSs (Virtual Private Servers) to host our web sites. They are located in Holland for best possible access times in Europe. We are usually using a droplet with 1 GB RAM, 1 Core processor, 30 GB SSD disk. On that we can run 2 or 3 Multisites depending on the number of subsites (usually 5-10).
We run Ubuntu LTS as our operating system.
To handle the stack (the programs running a web server) we use the Coach plan on ServerPilot.io. I also gives us supervision of the CPU, memory and hard disk space. It installs (2018) among other things PHP 5.4-7.2, Apache, Nginx, and MySQL. It also handles our SSL certificate for the https protocol.
A fantastic set of plugins to setup Custom Post Types, Maps, Views, and Layout for WordPress.
The more we use it, the more impressed we are with the flexibility and stability.
A few examples from this site
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