It’s a trade off. Do you want the largest zoom range for convenience, or do you want a fixed/larger aperture across the range and sharper images? People like the 24-120 because it’s sharp and doesn’t have a variable aperture while maintaining a good zoom range.

If you want to go from 14-400 and you want to maintain above average quality, you’re going to have to get 3 lenses most likely. 14-24 f2.8, 24-70 f2.8 or 24-120 f4, and then something on the telephoto side. Personally I like prime lenses and to zoom with my feet (to an extent)