W5000 does not block outside noise very well, it's somewhere on par with open headphones, leak out is not that bad actually.
D2000 provides better isolation, but of course not as refined and might need a recable to tame bass down and accentuate details, they are a bit blurry in stock form.
K271S provides an excellent isolation, very good resolution and tight, punchy bass, sounds like small version of HD650. Zu cable adds extra details and makes bass punchier and better controlled, sounds unbelievably good for the price, with velour pads (use AKG pads only, not Beyer) comfort goes up tremendously, but they are useless without proper amplification.
Somehow Proline 750 didn't work for me at all, terrible comfort wise, recessed midrange, metallic bright highs and uneasy overloaded bass. To my ears that was like a combination of worst qualities imaginable in a single headphone.
Good luck on your quest.