I won't talk about Holliday, but Hudson was not great in the role. Her acting was good, serviceable, but not great, it's clear to me that the range of the vocalist in this role can cause a great impression in people and that's what makes Hudson so talked back in 2006, any scene without singing it was clear that she was not giving a great acting performance, but acting in a musical is not only acting, the voice counts and I get why she got that award. Specially when her co-stars were Foxx and Beyoncé, two ok-ish actors.
At first I thought Riley was gonna be the same, but what I saw on that stage was a very controlled, understanding and nuanced performance of someone capable to not only belting the house down, but give you the minimal details of a woman that goes through A LOT. Riley was, indeed, great, for my surprise.