Re: USS Voyager vs USS Defiant
The Sovereign Class would win in a 1 on 1 fight but wasn't the point of the Defiant Class that you get a lot of bang for your buck? With the resources needed to build a single Sovereign Class you could probably build 8-10 Defiant Class ships and I doubt you'd need more than a few to take down a Sovereign.
But remember that Starfleet wasn't about warships, they built ships with multiple capabilities, the best example of this being the Galaxy class. The Defiant was only designed to fight the Borg, as was the Enterprise E along with it's numerous other capabilities.
"The first duty of every Starfleet officer is to the truth, whether it is scientific truth or historical truth or personal truth. It is the guiding principle on which Starfleet is based!" - Captain Jean-Luc Picard, 2368