What are some alternatives?
When comparing OpenWrt and MikroTik RouterOS, you can also consider the following products
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
Gargoyle - Gargoyle Router Firmware home page
IPFire - IPFire is a server distribution with intended to use as a firewall.
LibreMesh - An Open Source Sofware for Geek-free Mesh Community Networks.
ClearOS - A very good alternative for Windows Server, for free
OPNsense - OPNsense® you next open source firewall. Free Download. High-end Security Made Easy™. Offers Intrusion Prevention, Captive Portal, Traffic Shaping and more.