

Honestly, every hw that is not going automatically into a power save mode when not used is utterly crap, even my home grade switches are able to do so.
So, the only thing you need to do is to buy recent hw and of course not over size your hw necessities. But recent hw tends to be more expensive, so in the end, it is an excel driven decission.
And once this is said, be careful, some hw suffer more for a on/off cycle than from a continuous power on mode. Think in hdd power cycles or condensation/ salt-rust problems in high humidity areas.
Usually 2.5" hdd tends to be more silent. But they are definitely worse from a nas perspective and not so in the ratio €/gb.
The solution with non mechanical disks is by far the most silent, but prepare the wallet and probably a kidney too.