Efficiency - LED diodes are very electrically efficient, which could save you money over time (though the jury is still out when it comes to whether LEDs get better yields than HPS watt-for-watt). Additionally, where an HPS bulb needs to be replaced every few grows to maintain its brightness, individual LED diodes keep their brightness practically forever. With an LED grow light, it's almost certain something else will break on the lamp before any diodes start losing their brightness.
Plug-And-Play - LED grow lights are plug-and-play which means you can simply hang up the lamp over your plants and plug it directly into any standard electrical socket. HPS lighting requires the use of a ballast; for smaller models it can be built-in, but larger HPS lights generally need a brick-sized external ballast.
LED Grow Lights Come With Built-In Cooling - Along the lines of being totally plug-and-play, most LED lamps have heatsinks and small built-in fans to help disperse heat up and away from the lamp, which lets them run cooler. On the flip side, even a small HPS bulb needs extra help for cooling, usually by venting out hot air using a fan and ducting.
Customized Color Spectrum - It is known that the color spectrum of light affects how plants grow. Unlike other grow lights which are pretty set in their color spectrum, each LED diode can be configured to emit light of a very specific color spectrum chosen by the user. This means that LED grow light color spectrums can be adjusted and customized in a modular way that’s impossible to achieve with any other grow light.