Telegram has some clumsiness in it's UX too, which I find annoying (attaching a pic on Android, for example).

I'm usually pretty indifferent to UI so long as UX makes sense. But even I feel the difference between Signal and Telegram, so much so that I have friends on both and we use Telegram instead of Signal.

That to me is pretty telling - we know better, we promote Signal to other people, and would still rather use Telegram because of UI/UX.