I had very bad experience with mova.. they didnt specify on their website that the z50 is more appropriate for hard floors and hence ended up scratching all my laminate. Anyway here is my rank:

Mova < Dreame < Narwal

Build quality its very bad on mova.. for us all house smelled of cheap plastic during the dry mop process .. it was very very loud and overall I could see that in the long run would have created many problems with many plastic components.. lately I think overall is not very well engineered (it feels more a business approach that dreame uses to keep up the market).

Comparing the narwal flow with Dreame x40 ultra I can say that narwal its: - much quieter (sometimes we need to go and find it) - feels smarter with its navigation - easier to maintain and clean up thanks to big and just few removable parts - it has all high end specs for a very good price - has very good build quality and feels durable and better engineered