The biggest advantage of wavebox is that there are no dead spots, but the wave2k has its own interesting water motion that is a plus.... It all comes to personal pref like most in this hobby. In my personal opinion wave box is excellent for sps corals, you never have to worry about flow right from the start... even as your corals start to grow.. every small crevice gets water flow... there is just no comparision with anything else currently in the market....
I have a wavebox(running every 6 hours), with one 6000 (running every 6hours - alternating on multicontroller) with a return pump at 700gph(which is robably 500gph afte a 4feet head) on a 100gal... in total about 20-30x turn overrate, at any given time, and I see no flow issues, infact some colonies that where loosing tissue from the base on my nano has fully regenerated... It is one amazing product.