You’re weighing speed & energy usage vs cost. With a small array, HDDs power draw difference probably won’t amount to much and you may hit the RPi’s I/O bottleneck before fully benefiting from SSDs speeds, though latency would be better.

But TL;DR: If your goal is to learn and build something cheap, go HDD. If you hate it, you can upgrade over time.

Yeah… Just because you say you’d prefer to not take responsibility doesn’t absoluve you from responsibility.

Unless it does, in which case I will begin committing crimes and saying that constantly.