I'm going to go about this in no particular order: 
As much as a fan as I am of the design of the Baudo class star yacht, the fact that it's specifically stated to be favored by rich kids and the like means that there's a chance that we may encounter a pirates frequently. The fact that it's also favored by smugglers for the fact that it's more easily modified means that there's a possibility of the group being more frequently subjected to inspections. 

The Action VI, would be favorable option because of its sheer size, however the extra size also means more maintenance, which in turn means more credits spent, not to mention the costs of modifications to make the ship defendable from pirates that know these ships are meant to transport goods. Sure we stand to gain a good chunk of credits for shipping more stuff about, but when you take into account maintenance, the costs of consumables, the paying of the crew, and the bribes to authority figures and the like to keep from getting arrested, we'd either be cutting corners or dipping into our own pockets just to try and keep the whole operation from going under. That, or jacking up the prices of goods, which is never a good idea when you're working with criminals and big corporations with the resources to have you picked off. We'd be safer going with one of the smaller ships.

The Class 720 suffers from a similar problem as the Baudo, in that it's favored by smugglers because of how easily modified it is. Depending on the nature of our cargo we'll want to look into something a bit more inconspicuous.

It comes down to a bit of a toss up between the Citadel class and the GR-75, however the Citadel wins out in the end due to both the Gr-75's high maintenance requirements and the Citadel's versatility making it a fairly common ship to see in the galaxy.

tl:dr- My vote is for the Citadel. "The Milano" seems to be a nice name, rolls of the tongue well enough.