the best is determined by the way you want to drive it in my experience owning both i feel the m6 drives and feels better, its a bit more fun too. although, the clk 63 is a more respected car and has a sense of satisfaction coming with it. i personally love the m6 and still own one. like i say it all depends on what you need it for.
M6 destroys CLK in 1/4 mile
The 2013 BMW M6 has 32 valves.
The 2007 BMW M6 has a V10 engine.
The 2007 BMW M6 has 40 valves.
The 2010 BMW M6 has a V10 engine.
The 2008 BMW M6 has 40 valves.
The 2010 BMW M6 has 40 valves.
The 2009 BMW M6 has 40 valves.
The 2006 BMW M6 has 40 valves.
The 2008 BMW M6 has a V10 engine.
The 2014 BMW M6 has 32 valves.
The 2013 BMW M6 has a V8 engine.