Signal is quite slow at message delivery, to start with. It's not easy to know if a message was delivered at all. That's the main reason I almost stopped using it.
Secondly, Signal does not have multi-device support and multi-device sync. Coming from Telegram, where I can catch up on messages on multiple devices and choose to switch to a computer keyboard to respond with longer messages, as opposed to a small touchscreen keyboard, I very much prefer having the ability to use different systems. Signal's desktop "app" is just with Chrome and AFAIK, it needs to be authenticated every time (with Telegram, I authenticate my desktop app once and it works fine across restarts). It's still tied to one device (the phone).
Wire allows users to signup or find other people using phone number or email address. Even Telegram depends on a phone number as the sole identifier for a user.
Overall, none of the current set of messaging apps or platforms are extremely appealing to me. All of them have some drawbacks. My dream platform would be a "decentralized and federated" system like email without having to be in individual walled gardens.