Streamlabs - Streamlabs lets you donate any cash amount via PayPal, with an alert displaying on my stream with your message if I happen to be streaming at the time. (supports PayPal, requires Twitch/YouTube login)
Twitch.tv - I am a Twitch affiliate, so you can donate to me via Twitch subscriptions (included free with Amazon Prime) and "bits". Twitch has a payout threshold of $100 on my end, making it not ideal. (supports PayPal and cards)
If your only option is to donate via cryptocurrency, email me, webmaster (at) this domain name, to arrange a method of payment.