1: Variety of lenses. When I was into photography ~10 years ago, you could buy 4 different Canon 70-200mm lenses; an F4, F4 w/ image stabilisation, an F2.8, and an F2.8 w/image stabilisation. This meant that they had a great bit of glass within multiple different price ranges, and it made it much easier to get into their ecosystem.
2: The menu system on Canon cameras is really logical, for me. Nikon menus have always confused the hell out of me.