I believe Ocado to be a more ethical company than the major supermarket chains. I believe they are more supportive of suppliers and a lot of their stock is Waitrose badged. Waitrose is a partnership organisation and I therefore feel their "staff" (or partners) get a better deal.
I may be mistaken in my beliefs, but until I find a better way, that is where I choose to shop. I don't have access to a car, so local or delivered are my main options.