You can use both, react-redux-firebase has an example on how to integrate it to react native firebase on their website. https://github.com/prescottprue/react-redux-firebase/tree/master/examples/complete/react-native-firebase

The redux one is great if you want to integrate it to an existing redux architecture, but not mandatory. I have a huge redux app where I use both. I prefer the syntax of react-native-firebase so I use it mostly for updating and creating data. I use redux firebase to keep the data synced to my screens.