Based upon sales Ford is the most popular of the "Big 3."
Now, does most popular = "best?"
Sometimes it does, sometimes it doesn't.
I like my F250 but am heavily leaning toward Ram for my next truck. But hey, I'll test drive them all, Chev/GMC included. Freedom of choice and shopping with an open mind is much more my style than showing brand "loyalty" to a hunk of steel & fluids that couldn't pick me out of a lineup even if I drove it daily for 10 years.
In my mind, they're all so close in price, performance, and reliability that it comes down to personal preference and factors like how the seats fit your caboose and which interior appeals most...subjective things. I just don't see a clear-cut winner. They all have their strengths & their little quirks, and they are all seemingly getting better with each generation.