Which would be more worth the cost (about the same price total):
1) D2000 (w/ Lawton mod + Angle pads)
2) D5000 (unmodded, original pads)
(fyi--I'm still having trouble finding a near-mint condition pair of D2000s for a reasonable price. If anyone knows someone or some place that's selling a near-mint or new pair, please let me know!)
This would entirely depend on what you plan to do with these headphones. The only difference between the stock D2K and D5K are the cups and cable. Personally, I believe the cups make a noticeable improvement. Both headphones would benefit from angled pads and the Lawton mod, and it appears that you have this benefit with this particular D2K that is for sale. Work out the numbers and decide what is bast for you.
A pair of unmodded D5K would probably be worth a lot more on the market if you intend to re-sell them later.