Check out Talkyard: <a href="https://www.talkyard.io/blog-comments" rel="nofollow">https://www.talkyard.io/blog-comments</a>. It's like Disqus but open-source, or hosted serverless (I'm developing it).<p>You can add custom CSS (although some HTML class names might change, right now).
The main problem I have with Facebook comments is that it's harder for them to match the rest of your site, visually. Disqus comments usually seem to look more integrated to me. I'm not familiar with DIY so I can't speak to them.