Let's keep it simple. I'm sure most of us are proud of Docker CPU cycles charted in Grafana via Prometheus, but I'm talking about the house as a whole.

My personal favorite is turning out to be Mealie.

I self-host a bunch of things for my personal use, but Mealie definitely takes the cake in terms of benefitting the entire household. I like the meal planner and the ability to hit the supermarket once to get all the necessary groceries for the week (I've never been able to achieve this before). I don't think there is anything in my stack that even compares with the benefits my house gets of out Mealie.

My runner up would have to be any of the self-hosted media players (Plex, Jellyfin, etc.), but we also have Netflix and a bunch of streaming services, so not that impactful. Home Assistant would also be a close runner up, but it only provides great benefits for me, not the rest of the house. I think Immich will be on this list shortly, when it matures a bit more (are we able to import existing photos yet?)