Well, let's say, "if you want to operate internationally." For those countries which produce their own charts, their format can be very different from each other. Jepp chart subscribers have the advantage of consistency in presentation across borders. All the essential information is in the same place.
Beyond that, it's, as
@EdFred said, purely a matter of preference.
@bflynn, I used to have easy access to both. I flipped back and forth between them. The differences between Jepp and the US Govt charts used to be far greater, especially in the pre-briefing strip days. Those differences combined with better quality paper, clearer printing and loose leaf binders (not to mention the mystique of being the charts the airlines used) led to what most saw as a decided advantage to Jepp. The real differences now are pretty minimal, but as we all know, belief does not go away easily.