In the same time you could commission SIX Robinson IIs and have the equivelant of -
...
Yes your one Battleship could smash a Robinson, but while that is happening the other 5 are raiding your supply lines...
Disputing an aspect of your math: given the 250kt/year production capacity, it takes ~8 years to build a McKenna, during which time you're only going to build five Robinsons, not six. There's no reason to artificially inflate the timescale to a decade other than to give the Robinsons an extra sister ship, which is highly questionable. The Robinsons still possess a greater total of most of the figures you chose to quote, but the McKenna has superior raw damage compared to five Robinson IIs. Something else to bear in mind: the raw numbers only tell part of the story, as the McKenna has much better bay sizes, for example, giving superior bracketing capability and thus superior accuracy. More importantly, only the ASF and DropShip capacities matter, and the latter only for the possibility of carriers, the rest is just noise.
As for what the other four Robinsons are doing while you're feeding one to the McKenna - although I'd have to ask why you're doing that; just avoid it like the plague unless you're going to force a fleet action to kill it - the outcome depends upon whether they're operating independently or teamed up. If they're all operating together, then you effectively end up with equality: both sides have a single powerful WarShip-based force. If they're operating individually, a Robinson II is a more viable target for a realistic ASF attack by whomever you raid.
By realistic, I mean a few dozen ASFs, perhaps with DropShip support, enough to counter the Robinson's carried craft and get a solid strike through to the WarShip itself. A cruiser like the Aegis takes about 60 ASF to kill as I recall from Jellico's testing. The Robinson II has roughly comparable carried craft, armor and SI, but massively weaker armament - forget about its standard weapons; apart from that stern LRM bay, they're pitiful, and even that bay can only shoot one ASF/Capital fighter squadron per turn - so it's less capable of fighting off a determined ASF attack than an Aegis.
Also, raiding supply lines is much, much harder than you might think and a waste of a WarShip's time and capabilities.
Personally, I'd keep my Robinsons together until the McKenna was dead and even then I'd never operate them alone.
As for the original question: given the superiority of ASFs in aerospace combat, if I was forced to field a WarShip for this scenario I'd opt for whatever carrier is available - so Leviathan II, Thera, Feng Huang (Upgrade), New Syrtis, Conqueror, York, Samarkand II - whichever gives me lots of 'free' ASFs due to their built-in bays. I'd avoid the Fox/Potemkin types, because exploiting their DropShip capacity to transport DropShip CVs is just one exploit too far for me.
