I briefly looked into Gramps, but found that it wasn't the best fit for my needs and interests. What do you enjoy about it?
I think my Dad used GSP Family Tree for a while, but I've since switched to WikiTree. I like their goal of building a single world-wide family tree and they offer a nice balance of privacy and collaboration. While it is not fully open-source, they have some decent reasons behind this decision.
I've heard of webtrees as another FOSS genealogy application, but collaboration didn't seem as easy as with WikiTree.
Does anyone know of any federated genealogy platforms? I think this could be another possible software niche for the fediverse.
P.S.
FOSS software
Free Open-Source Software software? You'd better not forget to put your PIN number into the ATM machine :)