Onions from seed?

I have sown some onion seeds now in modules, not for any other reason than I was at a loose end, have also sent for other onion seeds as I am trying to find ones that are nice when eaten raw but not sure whither it's down to the veriety or if it's soil conditions which determines the taste of onions

My dear auld Dad used to eat an onion like an apple.  The large Kelsae and Mammoth cultivars are very mild because they have been bred for size not taste.