I like how easy it is to set up filters with this software! It's very simple in comparison to other mail server programs out there that require more steps/knowledge or time spent setting them all up correctly first before they work as intended - which can take some trial an error getting right sometimes (especially when you're not familiar at putting together systems).
The price point could be lower too? But then people would complain about cost cutting measures so maybe best just leave well enough alone?!