I've been very pleased with my XX setup. I had some rear shifting trouble with it at first, but for the last year, it has been more reliable than anything else I've ever run. I think XTR shifts just as well. Don't think you can go wrong with any of shimano's nicer stuff. As far as sram goes, I would stick with X.0 or XX.
I think the magura MT8s are the highest performing brakes on the market right now: if you're concerned with weight and ultimate blingability. Otherwise, Shimano's XTRs are very, very nice, as well as XT and SLX, but you're paying a small weight penalty over the Maguras. Stopping power of either of these two will be comparable. The Formula R1s, in my opinion, have the potential to be the highest performing brakes out there, but rotor clearance is basically zero, so you will have a constant battle with pad rub. Hopes are reliable and well made, but stopping power versus weight is very poor. Avid's quality control is poor, and their design (taperbore) is flawed, though they can perform allright. I'd rock some X0 trails if they were given to me.
King hubs are reliable, fairly light, reliable, build stiff wheels due to their high flanges, reliable, have quick engagement, and are reliable. Some kings laced to arch rims would build a pretty stiff and light wheelset. 29er factory wheelsets have improved quite a bit: especially the nicer Mavic wheels, but the rims are narrow if you're into running wide, thin casing tires.