Element X is the faster matrix client which will eventually going to replace the Element App on Android & iOS.
The App is currently Available for iOS in App store & Android build is currently not provided but you can test the pre-release from here Element X
I haven’t tried Element X, but I’d like to recommend SchildiChat as a good matrix client for desktop and mobile. My understanding is it’s a fork of element, but it works much better and more reliably in my experience. Element was very inconsistent about fetching messages for example.
meaning Android, no iOS
From their own FAQ: