Nice tank and nice view!
A lot of what you choose will be dependent upon what you are going to keep in the tank. I will make a couple of recommendations....
1. If the system will be predominantly sps corals / clams I would recommend going with the Sunlight Supply or PFO Mini 250w DE pendants. The SLS and PFO units are by far the best DE pendants on the market when it comes to putting light into your tank. The SLS edges out the PFO, but those two are in a league of their own.
A Hamilton 14k gives a really nice balance of white/blue when ran by itself. Pretty much all the other lamps on the market are either going to be a little more blue or a little more white, the Hamilton 14k really isn't comparable to anything as far as coloration goes. It does however lack a little bit in intensity, but in the size of tank you are looking it there shouldn't be any problems.
The only downside to this setup on a cube tank is that the light distribution is not exactly square, where as it is more of a rectangular shape. You will have a little more light "spill" to the left and right or front and back depending on how the pendant is oriented over the tank. You can however lower it some to help alleviate this problem.
2. If the system is going to be more softs/lps with just a few higher light animals then I would recommend Icecaps new flood/spot pendant using a the 20k par36 bulb available for it.
The color is very pleasing, and actually gives out a fair amount of intensity (read: PAR) for only a 150w bulb.
The really nice thing about this setup is that it is perfect for cube or pentagon tanks, where you are needing the same amount of light coming off each way of pendant. You will have more light control with this pendant, having less light spill over the edges of the tank and keeping it all inside.
If you have any questions on anly of the setups feel free to ask. HTH