If you can afford it I would definately suggest doing the type of system that is reef ready (pre drilled) or something similar. I'm not totally sure if you are talking about biocubes, which have everytihng (filter and pumps) housed in the back of the aquarium, or if you mean the tanks that are pre drilled that have overflows in the aquarium.
I'm going to suggest going with the reef ready aquarium, where everything is pre drilled and all you have to do is provide the sump,fug,wet/dry, filtration, and pumps which are usually housed under the aquarium. This is good for two reasons, one it is MUCH more flexible in terms of what you can do, you can increase your water volume by doing this and you can also chose the type of filtration that best suits your needs. The second reason is looks, no one likes having a skimmer or filter hanging off the back of their aquariums (i sure don't), so you can hide all of that stuff under the aquarium (or elsewhere) with a reef ready setup. I guess the only downside i see to this setup is possibly cost, sometimes these tanks costs a bit more, but not by much and are well worth the investment - i wish i would have invested before jumping in and purchasing a regular 30 gallon. Now i have all this stuff hanging off the sides of it.
My vote would be a reef ready (pre drilled) tank. Just my 2 cents.