I have always used a non-bio powder. Because that's what my mum used when I lived at home.
I sort of assumed that it was good for sensitive skin but I don't know why! 
Can you tell me what you use and why?
Fwiw I use aldi non-bio and no fabric conditioner (often irritated by the strong smells). Our washing comes out clean and washer drawer isn't full of slimey gunk.