Signal has most of the problems that has WhatsApp: mainly the fact that it's dependent on a smartphone, yes you have a Chrome-based application that is the same as WhatsApp web, it's only a remote interface that connects to your phone.

Telegram in my opinion is far better, it's completely cloud based, you can use it from whatever device you want, it has real desktop apps, you can send files, you have bots, channels, large groups, usernames, you name it.

I don't get why using Signal, yes it's free software, also Telegram it is (ok, the server is proprietary but even if you have the source how can you be sure that what they release is what is running on the servers ? If you don't run your own server the source are useless), but I don't see other advantages, so why bother with a third messaging app ? I use WhatsApp for the large user base, and I use Telegram for the advanced features if I need them.