And personally I don't get why Sisko wanted another Defiant class ship.
When is it ever stated that he wanted
-class ship? The only dialogue about the vessel happened in "Dogs of War" when Dax stated that she didn't realize they were getting another Defiant
-class ship. Sisko says nothing about wanting
that type of ship.
In any event, it's not surprising that he would get a ship similar to what he had before. Sisko helped design the Defiant
and his crew was familiar with the vessel's systems.