The ecosystem can definitely use more work, but I've found maddy to be really good, because it's all in one, makes very reasonable choices, and is easy to configure.

I put maddy first because it's what I personally use (without dovecot) -- I make sure to back it up as well, and that's enough for me/most people, I think. It's the closest to the whole package which doesn't rely on.

Oh you know what, I completely forgot about iRedMail:

https://www.iredmail.org/

I haven't run this, but it's another great option when combined with SoGo.