Originally Posted by horatio
I agree, the two (or three in case the third one was finished when the war break out) NX-class starships are the most advanced human ships and humankind probably focused on quantity, i.e. smaller, slower but hopefully armed-to-the-teeth ships during the war.
These kind of ships would also fit Spock's descriptions in "Balance of Terror".
I like to think that the Daedalus-class
began its existence during the Romulan Wars as a easy to mass-produce, no-frills Earth design that remained in service after the Federation was formed as a much needed "a dime a dozen" workhorse...
...whereas the NX-class was discontinued after only ten years because it was a more elaborate and harder to mass-produce design that perhaps couldn't be modified to accept the new Warp 7 engines being developed at the time.