BizHawk is a multi-system emulator designed predominantly around the production of Tool Assisted Speedruns (TAS). It is written in C# and requires .NET 4.0 to run. BizHawk focuses on core accuracy and power user tools while still being an easy-to-use emulator for casual gaming.
Like RetroArch, BizHawk uses cores to emulate consoles. Go to http://emulation.gametechwiki.com/index.php/BizHawk for a list of the consoles BizHawk supports and which emulators the cores are based on. More Info »
Full screen support
Controller and hotkey mapping
Joypad support (for both controller and hotkeys)
Auto/rapid fire controls
Basic re-recording and rerecording
Alpha version of "TAStudio"
RAM watching/poking tools
Libretro support (1.11.4 onwards)
For TAS purposes, this emulator is king. Since 1.11.4, It has support for Libretro cores, making it a good alternative for RetroArch, and adds TAS support for all compatible cores.
BizHawk is a very good alternative Multi-System Emulator to RetroArch. If you are not a fan of RetroArch's controller-usage GUI and prefer a mouse-usage GUI like what other standalone emulators use and if you enjoy making speedruns then give BizHawk a try.