Let's throw a wee bit of objectivity into the mix, shall we?
Above, you see a FR & phase rotation plot for the Senn HD-800 which is extremely, extremely good!
Above, the FR & phase plot for the LCD-2, which is arguably, better through the midband and bass.
Above, Sq. wave response for HD-800, again, remarkably good.
Sq. wave for LCD-2, again, arguably, a bit better, less ringing & better pressure gradient.
Above THD & impedance plots for HD-800, really really outstanding, slightly better than LCD-2 in HF THD.
Above, THD & impedance plot for LCD-2, very close to HD-800, but more consistent, and of course, no reactive impedance.
By the numbers, these headphones are very close in capability, so the difference will distill down to mostly subjective issues and individual HRTF match.