I personally think this is gonna come down to the characters themselves. They all have enough weapons and powers to counter whatever may be deemed as an advantage, and they've all faced physically superior, power based characters, so they're all pretty comparable in ability to take down armies of baddies. So in my mind, it all comes down to the more personal details.
Just putting it out there, Delta is a seven foot tank and fairly agile at that. Guy is stronger than both Jack & Booker, they'll need to team-up to take down Delta and even then they're not winning up close. They'll need to team-up on Delta and keep their distance with some guerrilla warfare style combat, which Booker should actually know. That's the only way they're beating Delta.
Now let's assume they do beat Delta, he's the bigger guy so it's logical they would try to take him down first. So if it's now Booker Vs Jack, I'm giving it to Booker. Why? Jack has no formal training, In-Character he's just sorta getting lucky in Bioshock 1, and does get good at doing what he does (killing splicers and Big Daddies), but Booker is a war vet. Booker has the skills, the training, and superior experience in my opinion to know what he has to do to take down Jack.
So let's recap. Booker is probably gonna be the guy to convince Jack that they need to work together to take down Delta. Delta is still a walking tank, he still has a chance to win, but it's less likely as long as the other two manage to keep their distance. Then once Delta is down, Booker should take the win over Jack due to superior combat training, and combat experience. No comparisons to any other characters should apply here, like Booker taking down a Handyman, or Jack taking down Big Daddies, cause they've all taken down superior characters to themselves, making them all comparable in that aspect. Bottom line is, they've never faced characters as versatile as themselves, so they should be judged by their own personal stats. So if Delta doesn't win, then I'd give it to Booker.