The fanboy BS in these threads is over-the-top. It's likely best to ignore people who say "everyone" and "all of the trucks." It's not so black and white.
I do construction work. I've been running GMC for the last few trucks; both gas and diesel. Great trucks. My trucks have done thousands of miles offroad, heavy towing, heavy hauling. No major issues or problems with the IFS over hundreds of thousands of miles.
Most of the bigger companies buy whatever they get the best deal on. My local utility district bought a bunch of GMC trucks this last round, and Ford before that. Every truck has its pros and cons.
Right now, it's more about availability and pricing. Both are horrendous around here.