In my RSSOwl client I have;
#1. Hackers News (YCombinator) of course ^_^
#2. Medium.com UnOfficial Front Page RSS (shameless plug)
http://feeds.feedburner.com/gotux/medium
#3. SlashDot RSS
#4. Hack A Day Blog RSS
But I find my self using "Polly" twitter client and following various people, websites and news this way.