The Jeep better or not? Who knows, your not testing apples to apples, but the modern Jeep has to be concerned for NTSB modern roll over standards. The Bronco had no such standard at the time it was built. Their are enough nasty pictures out there to cause concern for anyone out there really trying to protect life and limb. For those people go buy a Volvo.
As for top heavy cages, while a concern, it may be a moot point with heavier tires, heavy bumpers and heavy sliders not counting a whole bunch of other modifications. Center of gravity is one thing that counts, but for me wide soft sidewalls on the tires are a bigger concern. its more than just going up. Ask Ford about the old Firestone 500 Tires, or the mess with the safety riddled Ford Explorers. Bad shoes and you trip over your own feet.