Which Matrix server implemetation do I choose in 2024?

Hey, I'm fortunate enough to upgrade my home-server. I'd like to make some future-proof decisions. Which Matrix server do I choose? Dendrite? Conduit?

I like the candidate to be halfway well maintained, have active development during the next 4 years... Would be nice if it had a solid technological base and wouldn't hog that many resources. I'm okay if it still has some rough edges as long as they get ironed out in the near future.

It needs to provide service to me and a few friends and family. Audio calls would be nice and I definitely need it to connect to the Mautrix-WhatsApp/-Signal bridges.

Did I miss something? Is there another good server implemention apart from Synapse/Dendrite/Conduit?

Bonus questions:

1. Is Synapse the only server that can connect to SSO? Ideally I would like to maintain the user accounts via Authentik/LDAP/...whatever...
2. Is there a server that can handle multiple domains? Like an e-mail server that I can just tell "you handle mail for the following 5 domain names?"