Flour recommendation? Demeter/Kialla/Wholegraun

Hi I'm just asking for some recommendations for flour. I'm still new too Sourdough I've been purchasing organic bakers flour from local health food store in Brisbane (the sourced bulk foods). I'm interested in buying bulk e.g 5kg-12kg. Have noticed a few brands Demeter, Wholegrain, Kialla. Does anyone have any experience with these? Or other recommendations? Thanks