I love ATs but in your situation i would let the W2002 go. The price you can get for it right now as compared to what it cost 5 years ago NEW makes it a no-brainer. It was cheaper as the W5000 is today, W5000 = 120000 Yen, W2002 = 100000 Yen, take off the usual 25-35% for it's real streetprice)
Also it's a quite a step below the W5000 technically, though it has a different tonality and soundstaging.
From all ATs its my least favourite due to price/sq ratio, taking the current going price. For the old price it was ok and if you take the optics into consideration a great buy, but with todays 2nd hand prices, "no way"
Not a big fan of the K1000 so i would let that one go too..
I havent heard the O2 but from reading alot about it i'd say its the best allrounder.. or to say it in another way: neither the AKG nor the AT are big allrounders in my opinion. ymmv