Based on the websites looks like the Pavilions at Amanjena are larger than the 1 br riads at the RM. I stayed in a Prestige Riad (2 br) at RM where we had a proper dining room, office, living room (downstairs and upstairs), and a plunge pool and terrace which was very spacious - however it's listed at 430 sq m vs 140 sq m for the base riad which is a pretty substantial difference so not sure how the latter would feel.

Having visited both properties, while Amanjena is well designed and very nice, it's not as visually impressive as Royal Mansour which was a vanity project. Hearing from the taxi drivers, shopkeepers, and tour guides, it definitely appeared most viewed the RM as the top option in town. For example, the RM provides exclusive access to Serge Luten's House for its guests which is an architectural marvel - they randomly upgraded our airport transfers to a Rolls Royce. There are many small touches that make no financial or logical sense at just happen the RM - for some it may very well be over the top.

The Amanjena opened in 2000 when outside La Mamounia, the best option in Marrakech were upscale riads - I have no doubt it was by far the best option then. But with the RM in 2010, 4S in 2011, MO in 2015, and Oberoi in 2019 (and even a tier below with the Fairmont in 2017 and PH coming in 2024) you have a lot of good options. Outside the RM, all of those properties is in the outskirts offering a "refuge" from the medina (which isn't that chaotic imo and barely felt in RM or La Mamounia). So today, if you don't have the best location, F&B, hard product, or amenities you'd need to really be above the pack in the service to be the top dog, but I don't think I've heard or seen that the Amanjena though no fault to it - it's just the other options are also very good. If money isn't a big issue, do the RM. Just my two cents.