Both have their advantages. I flat tow mine and am generally happy with that decision, but I do think about getting a trailer at times.
Getting set up to flat-tow safely and legally is a bit of a pain. Setting the Bronco up with trailer brakes is the biggest issue. The RV market has some options (look for "toad" brakes). I set up my own system where an air cylinder pushes the brake pedal, but that's not a simple or cheap thing to put together.
The tow bar is an issue of course, but that's obvious so I won't talk about that much.
Once you are set up, each trip involves some hassles. Protecting the transfer case is the first thing. I take the safe but more difficult path of dropping the rear driveshaft each trip. Putting the transfer case in neutral and locking the front hubs is another method that seems like it ought to work and a lot of people do, seemingly successfully. And just putting the transfer case in neutral and leaving the hubs unlocked supposedly works for some people, but Ford didn't recommend it and some have burned up transfer case bearings.
While you are flat towing backing up is a challenge. The front wheels turn the wrong way and you end up trying to plow them around sideways unless you get out and straighten them out every so often.
My mud tires don't balance well, so I haven't flat towed with them yet. That's not an issue trailering.
So I've painted a pretty bleak picture of flat towing but I still do it. Why? Because it doesn't require a trailer. Trailers cost money, they take up space (both at home and when in a camp site). Loading a trailer takes effort as well as requiring specialize equipment (tie downs specifically). It's not bad of course, but it's really no easier than hooking up to flat tow.
A tow dolly is the in-between option. Cheaper and smaller than a trailer. Simplifies the braking issue of flat towing. You still need to deal with the transfer case (some tow with the rear tires on the dolly and the steering wheel tied off, but I've heard enough horror stories that I don't think I would).
In reality none of those are bad options. People do all three and people will strongly support their choice. So you need to decide what option will work best for you.