I don't remember how I first heard about HN, but I came here from SlashDot, too. At some point, I realized that /. was too many fluff posts (I can't say now exactly what the "fluff" was, but the perception was very strong for me), too few posts that I was interested in, and that I had just grown tired of trying to dig any gems out of comments that had become increasingly toxic, boring, or irrelevant.

I remember when I first visited HN, after an initial bit of confusion, I realized two important things. First, there was no stream to follow...no need to feel like I had to "catch up". Second, I could scan 30 posts in the same time it took me to scan maybe 6 /. posts. The presentation was just so much more clean and efficient.

After about a week, I noticed a third really important thing. For the first time in ages, I felt like I was actually finding out about tech news as it happened instead of being days-to-weeks behind the leading edge. I was spending the same time/effort on HN that I had on /. (and mostly just staying in the top 60 posts), but getting much more for it.

That having been said, HN ain't perfect. Probably my biggest annoyance is the prevalence of links to paywalled and/or adblocker-hostile sites. But as far as news selection, I dumped /. just days after coming here and I've never looked back.