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I try and get away from carrying locks as much as possible. Since most of my rides are commutes to either work or school I leave locks there. For the longest time I didn't even bother locking my bike in the cage at work, but some heel stole my water bottle the other day and made me paranoid so I've got a u-lock there now too. For school I leave a u-lock and a chain with a padlock on the rack. I take them home over summer break and the winter holiday so they don't think they are abandoned there and cut them off.
When I do carry locks I prefer to wear a medium sized u-lock in a belt holster. Sometimes I'll wear a chain like a bandoleer if I think I'm going to need that as well. Depending on what bags I've got mounted on my bike that day the locks might end up there.
This is the simple, yet very effective holster I use:
https://www.missionbicycle.com/store/ulock-holster
The black one blends right in with my belt, but of course, that is the downside to using it, you have to wear something with belt loops!
I've never been a fan of mounting my u-lock on my bike. My bike is about as cluttered as can be without adding a u-lock! I'm used to the clutter of my fenders, lights, racks, saddlebag support and bag, three water bottle cages, Airzoundz horn, and bell, but I can't bring myself to mount a u-lock on the bike. Somehow all that other stuff seems to belong (to my eyes anyway!) while a u-lock would look ugly on my bike IMO.
That said, that Abus rack bracket looks pretty slick!