QuoteThe 24-105 is an awesome lens, and hands down the best single lens to own if you're only going to own one with a 6D -- assuming, of course, that you don't need something else for specialized photography.
+1. I think you probably also should have a fast prime or two in your kit. The available shallow depth of field can add nice drama, and the extra light can help with hand-held shots indoors.
I find myself using my 35/1.4 a lot.. but the 24-105 is an excellent lens