I really have not been impressed with the moog stuff I have seen in the past couple years when working on friends cars, especially for the price the parts stores charge for them. I went with Napa Chassis Parts' aka Napa premiums for lower balljoints, I only have a little over a month on them, but they seem to be quality to me, the japan made one was probably the best "aftermarket" Ball joint i've ever seen, unfortunately I could only find one, I had to settle for one taiwan made for the other side (I would avoid the chinese made ones, they looked rougher machining and finish wise than the other 2 countries). Napa also had a Sanki brand which appears to be japanese brand, I wanted to take a look at them, it showed in stock at all the local stores, but the inventory was screwed up on them and they didn't actually have them.
I have pretty much committed myself to OEM for tie-rods and ball joints at this point (besides the lowers, which you can't get by themselves) I've just had the best results, you pay more, but it lasts much longer. I've got OEM Nissan WD21 upper bj's on my SLR control arms, going on 2 years and still solid.