There are already a few threads on this, but in short: unless you meet each contact in person and compare fingerprints before communicating, Signal is a waste of time. Other messengers, including WhatsApp and Telegram, have far stronger authentication mechanisms for people who aren't willing to do fingerprint checks for each conversation. The need to share phone numbers before communicating is also a significant drawback compared to other messengers that offer usernames.
If you're only looking for a more private replacement for WhatsApp, Wire seems to be the best of class at the moment. It uses the same underlying encryption scheme as Signal, it offers the ability to share a username instead of a phone number, and metadata (call/chat/IP address records, etc.) is kept under Swiss jurisdiction. The main drawback is that its user interface is awkward and takes some getting used to.
If you're only looking for a more private replacement for WhatsApp, Wire seems to be the best of class at the moment. It uses the same underlying encryption scheme as Signal, it offers the ability to share a username instead of a phone number, and metadata (call/chat/IP address records, etc.) is kept under Swiss jurisdiction. The main drawback is that its user interface is awkward and takes some getting used to.