What are some alternatives?
When comparing RetroArch and RetroX, you can also consider the following products
higan - higan was formerly known as bsnes. The project was renamed after becoming a multi-system emulator.
MESS - Emulates most gaming systems that exist, emphasizing accuracy over speed.
LaunchBox - LaunchBox is a portable, box-art-based games database and launcher for DOSBox, emulators, arcade cabinets, and PC Games. Download it free!
Mame - MAME stands for Multiple Arcade Machine Emulator.
OpenEmu - Console and Arcade video game emulator for macOS.
Snes9x - Snes9x is a portable, Super Nintendo Entertainment System (SNES) emulator.