In my experience. I didn't like Murena. I used it for a while (I think 6 months. I don't remember well). And yes, it's "ok", but the interface is a bit broken.
The good thing is that there is a lot of software you can use there: OnlyOffice, NextCloud (much of their software), Searx and even Gitlab are there.
Another thing: if you like SMPT and IMAP, the Murena account offers you this. I prefer Proton, but it a good option too.
You're comparing apples to oranges as they say, Disroot is a volunteer group/organization who runs a suite of services (one of which is Nextcloud) which is intended toward a specific type of audience as a group of like-minded individuals; it is run by a named set of admins and is much closer to a foundation in an organizational sense which accepts donations to keep things running. Murena is a for-profit entity selling you Nextcloud-as-a-service without the underlying belief system which fosters Disroot.