I would argue that Riot (the official chat client for the Matrix protocol) is an even better option. It has all the features that Signal has, and then some. But most importantly, I believe— it is federated. The absence of the monolithic server structure makes it harder for anyone (government or private) to tap into the network or collect meta-data en-mass.
Another important feature: Riot is built on an open protocol, much like our e-mail works today. This opens up the possibilities to build an ecosystem of apps which uses the same login / ID, and the different apps can access and present the information in many ways. There are already several open-source projects underway, building micro-blogging services (effectively Twitter-clones) and I can imagine someone soon will try creating an alternative social network that can compete with the core functionality of Facebook.
Federation and an open protocol is important for the users and the free web, because it doesn’t create walled gardens.