Cannot tell about the others, never tried them. But here is my experience with fhem:
in FHEM you find support for all the sketches that come with MySensors lib and may easily configure any combination and number of current defined sensor-, variable-types. Serial and Ethernet-gateway are supported. (MQTT is supported as well (using the mqtt-client-gateway), but the as the MQTT-gateway is not as configurable as FHEM itself the support for custom sensor-types is limitted). In terms of MySensors-protocol it supports the complete functionality of Serial- and Ethernet-gateway (including configurable Support for Acknowledge, so an actor would get a message resend multiple times until it's acknowledged).
FHEM requires very little resources (it even runs on a Fritz-box, so a RasPi is more than sufficient) and is written in perl. The buildin-web-interface is a bit old-fashioned, but there are mobile clients for Android and iOS as well. Values are persisted on restart, they may be logged and rendered as SVG-Plots. Value-changes may trigger arbitrary Events (as being written in perl you may even run your own perl-code as configurable events occour). And last but not least the fhem-codebase is very mature. I run an fhem-server 24/7 on an alix-board (that is also my router, owncloud and print-server) to control my heating-system since nearly a decade now with very, very little downtime. As I usually do very little changes to the setup availability has been better than 99% during those years including all maintenance. For sure availability has been proven better than for the arduino-based ethernet gateways
But as a last word: as administration is not all point and klick a bit of technical interest (e.g. willingness to use a web-based commandline-interface for configuration and maybe some knowledge of regular expressions and a bit of perl) is helpful to explore the full power of fhem.