By improving the PF you will reduce the line currents and hence losses in the mains or submains.
You can also get away with a smaller size cable if PF correction is permanently installed, because of the lower currents drawn.
If the utilty doesn't charge for kVA's and has no thermal MDI's fitted, you can leave it without caps. although more copperlosses in mains.
As what WFO sais he is correct that normally you aim for a PF of 0.95, and not 0.98, that will be twice as expensive and will take a long time to pay back for the extra costs.
You certainly don't want to get unity PF with Caps because the risk of resonance. This can cause unstable mains voltages which may be a multiple of the nominal voltage and can cause a lot of damage.
