I am using WhatsApp for the most part, Signal for the sensitive stuff and Telegram for people, who think it is more secure than WhatsApp. I really dislike Telegram. However, Signal has a beta version without the dependency to the play services.
Besides these, I really like Wire, which just had a successful security audit and recently announced, that they want to open-source their server software.
I also like Antox based on toxcore, which is a really interesting encrypted messaging protocoll. At the moment however, it is still in development.
The one thing I wish for, is compatibility between WhatsApp and Signal, which technically should be easy, because the use of the same protocoll. This way, I could use a free app and still connect with my WhatsApp friends. But this seems to be a dream for now....