I use Signal's Note to Self. It's often easier than dealing with a notes app or file syncing for one offs or interesting links I want to read on another device.
I just use a 1-person Slack message for this. Split categories into channels.
I can also write my own plugin bots to respond to specific queries.
I considered Discord but I hate its UI, especially every time I go to the website it wants to do a phone verification. F that, I'm out. If you are a nonessential "fun" app you need to be as low friction as possible.
I use Slack for this too, mostly because its reminders work great for me. If messages are anywhere else I keep losing/forgetting them. I wrote a Raycast plugin that takes a screenshot and sends it straight to my Slack, then I add whatever reminder I want from there.
Discord is generally snappy but nothing beats Telegram. It just feels like the only remaining desktop client that actually makes use of native OS facilities.
Plus there are scripts to back up the said channels. With Discord I haven't checked (but maybe there are as well).
So mostly (1) Telegram is still snappier and (2) Telegram was there first, more or less, at least on my own timeline of checking chat clients.