The choice to use quicklime or hydrated lime depends principally on two factors: availability and consumption rate.
Not all lime producers have hydrated lime available. When they do there is a difference in cost between the two materials. The cost per tonne of quicklime and hydrated lime is often very similar, but the big difference is that a tonne of quicklime when slaked yields 1.32 tons of hydrated lime (the difference in molecular weight between CaO and Ca(OH)2).
To use quicklime however, you will need to install a slaker. We generally find that it is more economical for facilities consuming more than 4 tonne/day of lime to use quicklime. If you will be using less than 4 tonne/day, then the extra cost of hydrated lime is offset by the additional cost and complexity of the slaker.Related:What is a slaker, and do I need one?