That's kinda a thing , I look for colour and density, I've found cheeper flour has a less white colour . I'm totally up for the theory of buy the best you can or buy as local but blind I'd be suggesting some of the cheapest has the better quality (just on white)
I use their no 4 organic, seems nice and makes nice bread, but not got too much experience of things to compare to.
I use one of these, I think the 35l one but I can check in a bit, that I got from homebase, to store a flour and rice sack in
https://www.reallyusefulstorageboxes.co.uk/35litre-really-useful-storage-box-c2x12529639