I was going to say high quality quiet power supplies, bu tthe mention that you have good adapters actually sways me even more. I've been trying to figure out where I put hte modular cables for my current power supply to no avail and it's driving me nuts (Aaarr!).
Build Quality. You can tell they actually care about their products when you look in any in-depth PSU review that takes a Seasonic OEM'd psu apart. Dat soldering
I have 4 different Seasonic manufactured (corsair branded) power supplies running currently, some for nearly 5 years and not a single problem! Seasonic is easily the best in making reliable power supplies.