The main reasoning behind large ships like dreadnoughts, IIRC, is that they're able to carry more guns, bigger guns, or better shields and armor than anything else out there. That's why battleships were popular before the start of the Kilrathi war - a larger hull let you hold bigger reactors, which meant tougher shields and bigger guns. The Vesuvius' claim to fame was that it was a HUGE carrier, which meant it could dish out as much damage as a task force all by its lonesome... and its new armor and shields meant it was practically invulnerable to normal bomber attacks, much as the Kilrathi Dreadnought of Thrakath's was in WC3. I recall that the Vesuvius itself had to be killed from the inside, because it was so well armored and shielded otherwise... but this is an advantage that could be countered by improved torpedoes.
I honestly don't see the reasoning behind having the Nimitz-class carrier - at that point, Confed's got few enough shipyards to turn out NORMAL carriers, much less resource-intensive monsters like this one, which appear almost to be a ripoff of the Vesuvius in stats, except for the 'seven launch bays', which seems more to be a ripoff of the Midway in Prophecy. And I don't recall them having any 'unconventional' designs (that is, designs not based off pre-War carriers) kicking around during the war, or even until about 15 years after it was all over. The Tiger's Claw probably had the most launch and landing bays of any carrier that comes to mind, and they had.. four of them, maybe? I don't see a design like this coming out of Confed labs, not when they were hurting for resources and ships, and thus didn't have all that much time to spend on developing a whole new design concept, much less retooling a shipyard (a process that takes at least 5 years, IIRC_ to produce something like this.
The Vesuvius' more conventional design would probably win points in any evaluations of the two competing projects... though even that took some improvements based off of Kilrathi designs, post-War. The trend towards centralization in the post-Kilrathi War fleet was based on the idea that it'd be easier to support single hulls that carried a lot of fighters, versus multiple carriers; this is useful in peacetime, but in wartime would prove something of a liability as well, at least on the tactical scale.
Even the Midway strikes a better balance than this carrier does, IMO, if only because they've stuck to a very basic set of design concepts (carries several wings of fighters and bombers, is the nucleus of a task force in wartime or can be relatively self-sufficient in peacetime). This is like taking the Kitchen Sink approach to ship design - it seems to be designed so it can kill capships BY ITSELF via the AMGs and torpedoes, PLUS it carries 400 fighters. The 20 torpedoes means you have five loads per tube, which renders those tubes relatively useless after you expend all that ammunition in the first fight you get into. It's more heavily armed than even the Vesuvius is, relatively speaking, and that ship carried an ungodly amount of anti-capship weapons for a carrier. Yet it's almost as fast and well-armored as the Vesuvius, yet is somehow lighter despite its equally large fighter complement and heavier weapons loadout... and I should point out that the total in the bottom of the Nimitz description of 320+20 support craft does not match the 400+30 support craft that was listed as the number of spacecraft it carried in the table above.
I can see why Confed went with the Vesuvius.
