Choosing a DC charger's power output based on the highest number in the catalog is the most common mistake, and also the most expensive one, because that power rating gets paid for twice: once in the equipment, and again in the electrical installation behind it.
The right question isn't "which charger is fastest" but "how much time do I actually have available to charge each vehicle between shifts." If your vehicles have a two- to three-hour window between routes, 40-60 kW is usually enough, and noticeably cheaper to install.
If, on the other hand, your operation needs turnaround in under an hour, for example taxis or last-mile delivery vehicles in high-demand urban areas, that's when stepping up to 90 or 120 kW is justified, provided the site's electrical installation can support it.
A common practice in fleet projects is to combine power levels: lower-power chargers for overnight or baseline charging, plus one or two high-power chargers reserved for operational peaks or unexpected needs. This optimizes both the investment and the site's contracted electrical capacity.