It seems to all depend on your area, where you lock your bike and how long you'll be leaving it out. One of my locks is a (heavy) Kryptonite keyed cable lock and the other is a light cheapo keyed cable lock. If I'm just out running errands where my bike is out of sight for any length of time I'll use the Kryptonite. If I'm in a restaurant and it's within reasonable view I'll carry the cheap one. It also depends on the bike I'm riding as well. I've never felt the need for 2 locks in my area and when I commute it's in my office all day.