which are? price isn't exclusive to a certain brand, modularity still encompasses a lot of brands and aesthetics are pretty much ignored with PSU's as far as I know. I can understand like, consumer loyalty for things like GPU's and CPU's but what defines a psu by brand?
The quality of materials in the PSU's circuitry itself, capacitors, durability / longevity, how hot or cool it runs, if it's safe from power surges or not, how much it draws from the wall, the fan quality itself, etc etc