Im using the ansible matrix playbook with synapse for 3 users and a bunch of bridges. I choose this because I used to setup my docker container and everything myself up but i absolutely dont want any downtime on my communications just because a config is not perfectly setup. If im out and about i want to still be reached. The playbook makes it really simple and takes care of everything i want. Even things like sliding sync are setup with one line added to the config. https://github.com/spantaleev/matrix-docker-ansible-deploy

I run my own Synapse server with bridges to WhatsApp and Telegram, along with a few other services, using Yunohost. I haven't observed any huge resource usage, and I like the centralized management/update. One possible downside is that you won't get the latest versions immediately, the Yunohost maintainers take time to test those. I prefer the stability that gives me but if you want to be on the edge a docker setup will be better.

Do you need/like matrix so much that you want to self-host it in place of more admin-friendly alternatives? The client/user side of matrix is okayish, but everything else is terrible. The protocol is inefficient by design and that's not something faster languages will solve so expect your available resources to sink, all implementations suck in different ways, are highly incompatible, constantly changing and have you in a permanent stressful state of chasing the latest/breaking/testing stuff. The team in charge is in denial about a great many things, and lacks the deeply needed amount of focus and reality check to get things done (which I imagine has been a large contributor to more and more "institutional actors" dropping them recently, like France several months ago).

I could go on and on, but in short, I was at your place some time ago and the mess, disappointment and overall stress I found with matrix only compelled me to give XMPP a close look. Now I (and my users) are super happy with ejabberd and modern clients like Conversation/dino/movim make the while thing a very pleasant experience. Not all features of matrix are there, but I take reliability/predictability and simplicity over them any single day.

My experience has been that dendrite and synapse totally maxxed out the server I ran it on (100% cpu utilization for days on end), so I run conduit.

The one downside of conduit is it's a bit behind, so it doesn't support all the latest rooms, and it doesn't support spaces yet, and it has minimal admin tools so you'll want to create all the accounts you need then close logins because bad actors will try to create logins and get you banned from half of Matrix. That said, I can tell you that even on my piddly little server (an Intel Atom D2550), it runs Conduit, ejabberd, nostr, and lotide, and the server basically sits idle. I can't speak of bridges, unfortunately, because I don't really use them.

This is the guide I used, it worked well to set things up:

https://gitlab.com/famedly/conduit/-/blob/next/DEPLOY.md

Do not use Dendrite for multi-user setups if you plan to run bridges. Contacts handled by the bridges are visible by the whole server, which means that it leaks many information on your contacts (names, phone number, ...). I'm also not sure that multi-user puppeting is supported with dendrite.

I would advise you to run Synapse because of that.

I run my own Dendrite server and have had it work pretty well.

Initially I chose Dendrite over Synapse as I heard about Synapse being quite heavy in terms of load, and my overall experience with Dendrite has been pretty good!

I run the server just for myself, but have it setup with Signal and Messenger bridges that work flawlessly (apart from one time when Facebook thought my account was hacked and had to reauth!)