And if Sisko were in command of the Lakota?WHO is in charge of the ship makes a difference, and if Sisko were commanding, I think Defiant would have decisively defeated Lakota
I'd have to give it to the Lakota, since he knows the Defiant's weaknesses. Plus, he's....The Sisko. Give him an Oberth, and he might still win.

I was thinking about SubCommander's comments, and I think he has an important point about the Excelsiors being old tech.
Actually, I think that the Sovereign class came out of a project to replace the aging Excelsiors. Perhaps the project was well enough along that it was promoted rather than cancelled when the Borg appeared.
In the mean time, the Excelsiors in TNG still seemed useful, at least in milk runs.
In peacetime, the Excelsiors are probably still totally serviceable as far as most roles (scientific, diplomatic missions, patrolling the neutral zone, assisting planets of the federation with various issues). A wing of upgraded Excelsiors is still likely pretty deadly, too. I wouldn't relegate them to milk runs, necessarily, just that their missions as capital ships (like the Galaxies and Sovereigns) has changed, since they are no longer the latest and greatest. We see more Excelsiors than the Ambassadors, so they are doing something right, anyway.
But each ship is a culmination of what came before it, and I think the Intrepids just basically have everything the Excelsiors had, plus newer tech. They may not be quite as massive, but I think it is fair to say their structure maybe tougher, and their tech more advanced and efficient. I also think htye are faster and more maneuverable. We saw how Voyager took on ships many times its size and won, so I think size isn't that much of a factor. Besides since a single phaser blast or photon torpedo can destroy an un-shielded Galaxy class, all ships are relying on their shields, and since the Intrepids have newer engines that go faster, I think its reasonable to assume they are more powerful and can create more shield output for defense.