Michael Piller once said this in an interview:
"It was harder to define Sisko as a character than perhaps any of the others, and ultimately it took us probably a season and a half to reach the conclusion that Sisko was a builder, a man who built things, stayed with projects, as opposed to the driver, the captain of a starship who went off and moved from place to place."
If you look at Sisko's career, it's pretty consistent with that, even before they decided it. Between the Saratoga and DS9, he worked at Utopia Planitia, helping to design and build starships, including the Defiant. He helped restore and active community on DS9.
In season 4, we learn he was once offered a civilian job on Earth building orbital habitats. In season 7 he talks about building a house on Bajor.
If Sisko was around today, I imagine he'd be an engineer or an architect.