When I had the R70X and 660s1/2 all side by side, it was amazing how light the r70X was along with the fact it sounded like a Sennheiser moreso than typical AT open back sound. The earcups on the r70x is hit or miss though since the cups are smaller than the AD1k/2kx/x5k etc.
But the most comfortable over ear so far is the mdr-f1
For the 6 series, not all of them sound better when the clamp loosens over time.
In other words, some 6 series sound better as clamp loosens, and others sound better with more clamp.
Then you have some which sound better as the pad flattens, and others which sound better with brand new pads.
So, these things should be factored in IME