They can both still be helpful.
The second anti-sway bar can fine-tune your over-steer/under-steer characteristics, and axle/spring wrap reduction is still a good thing.
All Broncos have axle-wrap to a point, and it's even more with most of the modern springs. But it's rarely such an issue that you have a problem with it. Yes, it'll make the rear more stable and linear, especially under acceleration and braking transitions.
So yeah, it's "a thing" but it's not the be-all and end-all of things.
If they both fit with each other (and I think a couple of members here have done both) then I would do both.
If I had to choose, it might come down to your engine power, transmission type, differential gear ratio, tire diameter, and the weight of your right foot.
So, what's your combo? Sounds like a 4R70 trans? Full EFI as well? Maybe 33" or smaller tires? What gear ratios?
And how do you like to drive?
Paul