It really depends on your interests. Most mainstream programming languages have dedicated subreddits, so that's a good place to start. /r/programming is a great place for general programming news, but it usually overlaps with HN. /r/netsec is another excellent subreddit with general security-related news and content.

I think the beauty of Reddit is that it's all up to you to curate the content, which obviously makes it hard to recommend things to read for others :P

Here is a list of my favorite subreddits for anyone who wants an idea of what's available on Reddit:

Tech-related:

- https://www.reddit.com/r/cscareerquestions/

- https://www.reddit.com/r/webdev/

- https://www.reddit.com/r/androiddev/

- https://www.reddit.com/r/netsec/

- https://www.reddit.com/r/ProgrammerHumor/ (programming jokes)

- https://www.reddit.com/r/ReverseEngineering/

- https://www.reddit.com/r/emulation/ (video game emulation news and discussion)

- https://www.reddit.com/r/electronics/

Non-tech:

- https://www.reddit.com/r/AskAcademia/

- https://www.reddit.com/r/DepthHub/ (a better version of /r/BestOf)

- https://www.reddit.com/r/financialindependence/

- https://www.reddit.com/r/interestingasfuck/

- https://www.reddit.com/r/sciencefiction/

- https://www.reddit.com/r/shittyaskscience/ (the opposite of AskScience)

- https://www.reddit.com/r/VXJunkies/ (try to figure this one out :P)

- https://www.reddit.com/r/bertstrips/ (beware: offensive content)

- https://www.reddit.com/r/totallynotrobots/