I used to ask myself that question, then I realized it doesn't matter. Communities come and go. Slashdot used to be good. Reddit used to be good. That they're not anymore doesn't matter.
It sucks to up and leave a community once in a while, but it's not like you lose everything you did there. Social apps are intrinsically focused on the short term (past & future). It's okay to change which websites you visit once in a while.
I highly recommend Tildes. I enjoy my time there. It's pretty quiet and has very high signal, very low noise. If one day it has to be shut down because the bills can't be paid, that will suck… but there will be others.
Hopefully Tor isn't a problem. In the Age Of Snowden, I use it almost exclusively. Also might I suggest a .onion gateway (and maybe a .i2p gateway too)?
I worked at reddit for almost 4 years, but quit and started a non-profit so I could work on building a site that would be able to stick to the principles I believe are important: no advertising or investors, open-source, privacy, higher-quality content, etc.
It's not incredibly active yet since it's in invite-only alpha, but it gets several hundred posts a day and is coming along well. There's more info in this blog post (including how to request an invite): https://blog.tildes.net/announcing-tildes
Just send me an email if you're interested and I'll give you an invite. It's not intended to be much of a barrier, I just want to keep the growth controlled for now while we get base features and site culture built up.