Untill the refit Dadelus and Odessy hit Star Gate Atlantis now ship in Sci Fi destroyed ships faster than the Defiant.
It's some 10x more powerful than the Galaxy, highly manuverable well equiped and specificly designed to kill ships in record time. There is frankly no better combat vessel in Trek.
In fact I would put a Defiant class starship to win against just about any ship except a Voth Mother ship and a Borg Cube. It will go against Scimitar, The Dominion Ship-Killer, the Regents 4,000 meter Negh'var.
I admite I wasn't initially a fan of the design. It was a rapid depature from the Star Fleet norm but I had to start to reconsider after The Search Part one were this ship fire 6 volleys in 2 seconds missing three times and destroying the attack ship in three volleys. Nothing short of incredible can describe that preformance and ever since I've stayed glued to the screen anytime Defiant went into battle.
After looking over the model I appreciated Defiant in a whole new way. It had all the standard equipment, and including landing gear and three shuttle bays and a massive impulse engine. The features of the ship included the new sensor pallettes that would be later put on Voyager. It lacks some features but for this completely encapsulated warship it's forgivable.
All Hail Defiant.