mqtt vs serial gateway on RPi

[hasemar]

Hi all, first post! I'm hoping this is the right category for this question. (There should really be a newbie question section!)

I currently am running a RPi 3 with Home Assistant (hass.io) installed. I used the image download for RPi3 on the website.

I also set up the MQTT broker via the hassio interface. I have successfully been able to control a few Sonoff Basic switches via MQTT commands.

I now want to integrate some sensors, I have a few Arduino Nano's and some nrf24l01+ radios that I want to use.

After reading through the MySensors getting started turtorials, I am still confused about the gateways.
How does it integrate with my controller? Should I use a MQTT gateway or a serial gateway?

I think the concept I am stuck on is the transfer of data from the radio to the RPi.

I'm sure this is a common question but after searching the forum, haven't found a post that really clarified it for me yet. Thanks in advance!

Ryan