Good ux, pleasant to use. A large community and lots of channels with all kind of content. Api is also great for spinning a bot for whatever purpose. I have for example a critical error bot for a production server running. If a critical error occurs, I get an immediate telegram message.

If you’re ok with abandoning all security and privacy, then Telegram has some nice extra features that can come in handy.

Calling/ringing works reliably. My gf usually calls via Telegram to notify me and then we call via Signal

Signal can't do live location sharing

    Code blocks (let alone syntax highlighting) was the first thing my friend ran into after switching last week

In general, formatting on Telegram is a lot more versatile with >quote blocks that show up formatted as quotes and inline links without needing to have a giant message because of the giant URL

Many more image features, like you can do yellow highlighting and not only ugly shades of olive, you can put a message above an image instead of below, you can mark an image as spoiler, you can send it uncompressed, etc.

Jumping to a date was one of the first things I ran into

Web client lets you temporarily use someone else's computer without needing to install software

Making a Telegram bot takes 10 minutes if you just want a simple http callback and know roughly how it works. Signal has no support at all. Some third parties have made libraries but we keep having issues at work with our internal Signal bot to the point where I think we just gave up altogether now

Many people use Telegram to check if internet works because when opening the app it does a lightning quick check and it's very robust (I think it has no problem if DNS is down, for example) Looking at the title bar confirming that it works is much faster than trying to do a random web search

You can have memorable/pretty group URLs like telegram.me/OpenStreetMapOrg

Large files can be sent (also because of server-side storage not clogging up your phone, which is a double-edged sword of course)

Scheduled messages send at the right time when you're not online & the desktop app supports scheduled messages

Chats take a lot less space. The Signal authors probably don't have many contacts that they use Signal with because you can view the message markers of 4 chats before having to scroll down. In Telegram, 9 fit in view. Similar on desktop but both numbers are bigger. Messages are also more space efficient in Telegram

Telegram so so so much faster than Signal's web, ahem, electron client

The only advantage of Signal that comes to mind is the intangible property of privacy (and maybe local back-ups, so data availability, but then Signal doesn't provide software to view your backup data so is it really a backup if you can't test it and they can lock you out of the app?). I'm nevertheless switching everything over to Signal but it's often very hard to explain to people why they should give all this up for encryption. My family doesn't use all the advanced features but some techy friends do