There is no definitive answer to this question since both ETC and FPC solar water heaters have their pros and cons. Ultimately, the best decision for you will depend on your specific needs and preferences. ETC solar water heaters are known for their high-efficiency ratings, while FPCs typically provide better overall design aesthetics. Additionally, ETCs tend to be cheaper than FPCs upfront, but they may require more maintenance over time due to the use of warm-air technology.