Signal is good because it is easy to get others on board because of its simplicity, while having good encryption and security. However, SimpleX is just a better option. No phone number required, the same encryption, you can make a new profile whenever you want and you can have however many you want at a time. The groups can hold thousands of people. You can have it automatically make a new anonymous profile for you for each contact and group so that you can't be tracked across them apart from your writing style. There are no usernames, you add each other through links, which can be temporary or permanent, and you can add or remove a link whenever you want.
Sorry for that big wall of text, I just spat out all the things SimpleX is better for. I think that it's platform is the future.