I´m not sure weekends are the best actually
but if you choose weekends I think sunday would be better. But I think you can use the tool tubebuddy to suggest you the best time for an upload (i never used this feature though) I also think it depends on your channel and your content so it is hard for us to say if we dont know what your channel is about
I tried to upload on weekends once but it was no good for me...