Home Depot first choice (I am a contractor, go a couple of times a week) .
Lowe's second, slightly higher prices and not quite as nice product.
Harbor Freight is garbage.
Of the choices available here (Canada) Home Depot would probably be at the top of my list as well. Most of us live within a couple hours of the border and many will make a special trip to visit Menards.
Does anyone have a favourite US based alternative to Screwfix (i.e. general hardware monger)?