On a grand strategic level, fleet vs fleet, the Daleks would eventually get pissed off and blow up the galaxy, if that's what it took. I mean, remember in The Stolen Earth/Journey's End, they come up with a way to destroy the whole reality itself- the Borg have nothing on that.
This is the problem of comparing forces from fictional universes with wildly different standards of physical plausibility. "Of course Voldemort could defeat the SS -- his Death Eaters could just cast Avada Kedavra on them all! The Nazis have nothing on that!"
Plus you can arbitrarily pick the most powerful example of whichever side you want to win. The Daleks only tried to destroy reality once -- it stands to reason that at any other point in history, they lacked that capability, or weren't insane enough to use it. What if the Borg went up against the Daleks at a less advanced point in the latter's history?
That's why this kind of comparison is so silly. You can fudge the rules and parameters however you want. Of course the real answer to "Who would win in a fight" is "Whoever the writer wants to win." Indeed, arguing that the side with technological superiority is bound to win is contrary to the rules of fiction. Generally the side that has the overwhelming advantage is the one that's doomed to defeat, because it's more exciting when the odds are stacked against the heroes. The Daleks have a galaxy-destroying army and the Doctor has a screwdriver. The Borg have conquered a quarter or more of the galaxy and make Federation technology look primitive in comparison to theirs. Yet it's still the underdogs who win, because they have the rules of drama on their side.