I don’t think WhatsApp is a good option. Their clients are not Open Source, so it’s unknown if they really implement all the privacy features of the Signal client. Also, Facebook and WhatsApp are known to collect every single bit of Metadata they can get, it’s really bad. I wouldn’t touch it again, under any circumstances. I’m glad that nobody I know uses it, at least inside my circle of friends. Some still use it for outside connections or family members.