My PCs are always on in a shared environment, so my immediate requirement is quiet efficiency.
My gaming doesn't require the hefty power draw of multiple video cards, so I have found I can cycle a PSU into a couple of systems before putting it out to pasture in an HTPC or file server. I need a long-lasting, quality PSU, with mid-range wattage.
Quality of time, efficiency and price. cable management in cases improved enough where i don't care too much about modular. But i still like sleeved cables when i spend 100+ USD on a psu.
Really it's a lot of things just be a good product at a reasonable price and it's got me sold.
Long-term reliability and solid power delivery even at high loads. I want to not need to think about it until I know I'm pushing the limits of what it can provide
I'm building an intermediate gaming rig for my son in law from parts I've cast off. And don't ya know the 500w psu I had is total smoke? This would play real nice with what we have and make a little boy smile!
When I need a power supply, I look for something that is quiet and easy to manage. Seasonic generally make phenomenally quiet power supplies, and by the looks of this draw these also appear to be modular, so that makes it incredibly easy on my case space.
High wattage isn't a big thing for me, though I do need something to carry my 470. I just don't go overboard.
low fan noise and low heat output is definitely top priority, it kind of goes hand in hand in efficiency, since efficient units tend to output a lot less heat.
When I turn my computer on, I expect nothing but clean, efficient power from the power supply. My entire experience with the computer depends on whether or not the power supply provides me a solid power experience. Crappy power supplies provide a shitty experience whereas quality power supplies provide a good experience.
I look for the ultimate in reliability and durability in a PSU. Low noise, efficiency, etc.... means nothing if your PSU on your folding rig goes out and ends up taking everything with it.
I like to see psu's with a full set of connectors to cover most anything you throw at it. I bench on a torture rack and the motherboard of the moment is liable to be anything.