That said, it can be tricky to find RSS feeds with any consistent methods. I'm curious if there are some go-to feeds or archives out there.
Likewise, there is the HN RSS feed: http://news.ycombinator.com/bigrss
Also, all arXiv categories have RSS feeds associated with them: https://rss.arxiv.org/rss/cs
and you can also do individual subject classes within a topic:
https://rss.arxiv.org/rss/cs.LG
But of course if you're asking about my favorite feeds, I guess I'd have to say "my own". :-)