Matrix is fantastic. However, riot desktop sucks in my opinion. Yet again, an electron app. You say that matrix "has excellent clients for all platforms". That is simply not true at this time. For linux, there's pretty much only 1 client that's currently usable, and that is riot (electron app).
There's a fantastic one in the works, qmatrixclient (quaternion: https://github.com/QMatrixClient/Quaternion), but it doesn't support E2EE yet.