Well, every subreddit is an RSS feed (ex: http://reddit.com/r/artificial/.rss) so if you have a favorite sub or two, you can follow those in an RSS reader.
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". :-)
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