Tough call, and it depends mostly on what you're looking for. Definitely the K701's when considering price/performance. But in an absolute sense, I'd go with the W5000's because of their added warmth and overall musicality. They're more alluring, whereas the K701's lean toward the neutral side.
Not to muddy things, but I actually like the AD2000's more than either. Or at least I think so. All of them are excellent in their own ways. What I really dig about the AD2000's is that they are open and airy with a nice wide soundstage (although not as wide as the K701's). They also extract details quite well, much like the K701's. But the AD2000's also give you a more exciting presentation (the "good" AT coloration) much like the W5000's.
Oh, and I say "good" AT coloration because (IMO), not all AT coloration is created equally. I don't like the flavor they've imposed on the W100 or W1000. But I do quite like the AT house sound as represented in the W5000 and AD2000. Even that (the "good" AT coloration) comes across in a slightly different manner for each, probably because the W5000's are closed and the AD2000's are open.
Bottom line for me, the AD2000's reach out, grab me, and pull me into the music more so than do either the K701's (which are more neutral, present a wider soundstage, and are also very capable of "wow" moments) or the W5000's (which are more full bodied, robust and impactful, but missing a sense of air and excitement that the AD2000's offer).
Close call between the K701's and W5000's. The AD2000's seem to bridge the two quite nicely and are much closer to the K701 price point. They are also much closer to the K701 sound signature in terms of their openness and similarities in soundstage, but with an added bonus of a bit more of the "fun" factor.
Yet, I would be remiss if I didn't emphasize this: they are all excellent cans and I could easily live with any of them forever. At this level, you can't go wrong (forgetting the money you spend for the moment) but you really need to do your own listening.