Yea I've stayed at Atlantis The Royal twice now and it's just not for me. That said, the Club Lounge may be one of the best in the world (the views are pretty spectacular too but that's neither here nor there - there's plenty of other hotels with great views in Dubai).

I've never stayed at MBS, only visited it multiple times, and never thought "I want to stay here" - I think the Paiza Suites are one where I would consider that. As I said, it appears to me they nailed what Atlantis The Royal was *ACUTALLY* trying to achieve (from a luxury standpoint, not just from a monetary standpoint) with their hotel.
Atlantis The Royal makes many claims, but in the end it's essentially a slightly smaller version of a huge casino resort. The Club Lounge as mentioned is exceptional, but you don't get that feel of it being particularly small - everything is larger than life...in which case they may as well just have made a 1,000+ room property! And for all it's claims of luxury, I found the hard product at Atlantis The Royal to be somewhat lacking in terms of rooms/room amenities.
The Paiza Suites feels like a private hotel within a hotel (the madness of MBS in general aside).

Of course as I said, it was just a site visit - I haven't stayed there yet, but after many site visits to MBS, including to many different parts of the property, this is the first time I've ever thought "I actually wouldn't mind staying here next time".