Definitely Maria Feodorovna as Imperial Russian Court procedures stated "Dowager Empress always took first place, usually entering a palace room on the arm of her son-the Emperor, over the reigning Empress Consort."
It goes back to the Imperial Byzantium court customs, of which the Imperial Russian court was modeled after. More or less, Eastern custom verses Western custom.
Alix of Hess-Darmstadt was the favorite granddaughter of Queen Victoria, and she was raised by the Queen since Princess Alice, Alix's mother, died when Alix was just 6 years old. So Alix knew of Western court protocol better than Eastern court protocol.
Maria Feodorovna was a very popular Empress with the court, society, and the general public at large. Graceful, stylish, and tactful, Maria had 18 years to learn the ways of the Imperial Russian Court.
Sadly, Alix did not.
Alix was not at al popularl--inwardly shy, uncomfortable being in public, stiff, and rather an overly domineering woman who believed that SHE was always right, no matter what. Particularly when it came to her son, Alexei. Due to the blood disease ( Alix was a carrier of it from Queen Victoria and Princess Alice) that afflicted Alexei since his birth, Alix was over protective of him.
And Nicholas, being weak willed when it came to his wife and son, usually gave into Alix.
And yes, quite a few of the Russian Crown Jewels were at the disposal and use of the current Empress. Maria Feodorovna loved the jewwls, and wore them with panache and style frequently. Alix bitterly resented that fact that "Mother Dear" always won out.