After years of Sabnzbdplus’s reign, a new tool doing for the same purpose was born: NZBGet. In a few words, NZBGet has a lighter footprint on your system. It is coded in C++ whereas Sab is coded in Python. This means that NZBGet will run better on smaller system (such as NAS).
Configuring NZBGet can be pretty tricky for the first time, especially if you want to combine it with Couchpotato and Sickbeard and leave to them the post processing / renaming. I’ll write a little guide about this.