I have heard lots of good things about TryNinja's and LoyceV's bots. I personally use LoyceV's. The only reason I opted for that one is because I don't feel like using Telegram. TryNinja's bot (just like most other alternatives) sends notifications over Telegram.

Having a notification system is another feature that the forum needs to change and improve with the release of the new forum software. Such solutions should be made in-house I think.