The NX-01 in the Delta Quadrant would be interesting. Archer would probably not even have tried to get home (at warp 5, it takes 560 years), and instead gone exploring, and wouldn't really have realized how dangerous the Delta Quadrant is before Vidiians harvested one of his crewmen. They wouldn't reach the Borg any time soon, as it would take them 24 years to get to their space.
I think Kirk would do a lot of things the same as Janeway, as they are a lot alike. I really wonder how he would interact with the Borg, particularly eith Seven and the Queen.
The Enteprise-D or -E would likely make toast out of every Kazon that tried to put his grubby hands on their technology. Even those huge ugly Kazon battleships would hardly be able to scratch it's hull. I also think Picard would not make Chakotay first officer if Riker died, but 2nd. That's because there are 1000 people on the Enterprise, and 150 on Voyager, meaning the ratio of starfleet officers vs. maquis would be much greater.
If the Defiant was lost in the Delta Quadrant, they would also easily make toast of most enemies. There would likely be more, though (Hey, if you were an alien who wanted to conquer a ship, would you choose a ship with a thousand crew of nearly a kilometre long or one with 40 crew of a hundred metres long?). It would be a lot of fun to see Quark trying to earn profit at every planetary stop.