Usually, simpler (no electrical parts) is better.
Experience in rainwater harvesting system shows that A. although you may have a large cistern for storing rainwater it is almost never enough in a domestic situation, B. If the intent is to use rainwater for landscaping or gardening, the best place to store water is infused into the ground. C. If the intent is to use the rainwater as a potable water source, additional purification needs to be integral to the system. D. A metal roof is the preferential collecting surface as if it is without texture, it will wash cleaner faster.