I've been thinking about this, as I plan to go back to a "personal website on a domain I own" approach and can Facebook sometime kinda-sorta soon'ish. What software will I use? Dunno. I'm leaning towards something pre-packaged to provide the basic functionality. Probably a blogging engine like Apache Roller.
Beyond basic blogging facilities, if I decide to write anything custom, I would probably use Grails or Spring Boot just based on familiarity. Groovy/Java are my strong suit, so I'd probably default to that. Database would almost certainly be PostgreSQL.
And as somebody else suggested, I could see rolling with an NNTP[1] server. I could also see deploying Gopher[2] as part of my overall presence as well.
Heck, it might even be run to deploy something using WAIS[3][4] just for the lulz of it.
[1]: https://en.wikipedia.org/wiki/Network_News_Transfer_Protocol
[2]: https://en.wikipedia.org/wiki/Gopher_(protocol)
[3]: https://en.wikipedia.org/wiki/Wide_area_information_server
[4]: https://github.com/olsgaard/freeWAIS