I'd be excited to even start using Matrix for instant messaging. Elements seems pretty half-baked on my phone and I'd feel bad for convincing anyone to switch from Whatsapp to it.
On Android I quite like SchildiChat, which is a simple-at-first-look client.
Meanwhile, the nice thing about Matrix is you can use whatever app you like - e.g. SchildiChat is a fork of Element Android, FluffyChat's good too, so use whatever floats your boat.