Ello, which is billed as an alternative to Facebook, or in some reports as the anti-facebook. It's not the first alternative to Facebook that I've joined, but I like its style. It is no-ads, no tracking, a bit minimalist for my middle-aged brain to cope with...I feel like I'm blundering around in a white room with the doors and windows camoflaged and with an audience laughing just outside a door I can't see!
However, I'm liking the freedom from advertising, and the fact that it is currently all early adopters who are web-savvy and interested in a wide range of things who are on the scroll list.
You can follow people or set them aside in the "noise" stream... so it's more like G+ as a model for friending. I dunno... I think the social media model which is going to succeed will let us have multiple identities under an umbrella, and keep our different friend groups in different places. Currently friend simply means "interested in" on ello. It doesn't need to be reciprocal - so someone you friend may stick you in "noise". But I have friends who are interested in what I do in SL and not at all interested in genealogy... friends who are also home educators and interested in unschooling but not at all interested in my music. I need a way to keep all my friends happy and currently the only way to do that would be to develop different accounts for different groups.
What I really need is a combination of G+, FB and the late lamented Subjot, which was like twitter but divided into subjects. I loved Subjot, because it allowed me to follow someone when they wrote about genealogy but not to get all their "I'm on a train!" general stuff. It let me follow a lot of SL people whose other activities I had no interest in.
It's under development still, so I'll see how it is... but the lack of enclosed space to post things you only want your RL friends to see, is a big disadvantage.