It's not as simple as that though. TBH most cameras nowadays are much of a muchness in terms of output (sensor size relative) it's more to do with the system. As someone who's invested in a lot of Canon lenses, it would make no sense for me to switch to any other brand. And TBH you couldn't tell the difference between the final output of most of today's FF cameras. It's fine if you've only got a couple of lenses but to change to a whole system there needs to be more than a few hundred £ saved or a few more AF points.
I'm quite often trying other gear too, I have Canon, Sony and Fuji at home and Nikon at work. I'm still prefer my 6d to all of them