I love them both. For the rear, the T63 tends to be a little cheaper, which usually makes it a slightly better bargain IMO, but the D606 can often be found for about $80 on sale. Both perform very well, and they last about the same amount of miles.
For the front, I prefer the 606 for offroad duty.
Originally Posted by neo1piv014
Michelin T63 and Dunlop 606 tires are the 50/50 favorites around here from what I've seen. I've also seen some good things about the Pireli MT21's, though none are as cheap as the T63.