EmuNations

NanoBoyAdvance is a Game Boy Advance emulator focused on accuracy. It has been reported that its CPU and timing emulation is more accurate than other software emulators right now, as in CPU and DMA is emulated with near cycle-accuracy and ARM emulation handles nearly all known edge-cases. It also has an HQ audio mixer (for games which use Nintendo's MusicPlayer2000 sound engine) and quite a few nice post-processing options (ghosting simulation, color correction, etc.). 

Please note upon loading a ROM for the first time you will be prompted to assign the Game Boy Advance BIOS file. You can dump it from a real console (accurate) or use an unofficial BIOS (less accurate).

SkyEmu is a low level GameBoy, GameBoy Color, Game Boy Advance and DS emulator. Its primary focus is to provide a good user experience through a good mixture of tradeoffs of accuracy, performance, features and usability...

• Highly accurate Game Boy Advanced emulation

• Game Boy and Game Boy Color Emulation

• Experimental Nintendo DS support (only capable of running homebrew currently)

• Cross Platform: Windows, MacOS, Linux, Web App (with touch screen controls for iOS and Android)

• Game Controller and Rumble Support with configureable keybinds

• 4x Save Slots with screenshot preview

• Game fastforward and rewind support (supporting very long rewind times)

• Support for emulating the Real Time Clock

• CPU, MMIO, and Memory Debuggers

• Dark and Light Themes

• Support for loading official BIOSs dumps

mGBA is an open-source modern Game Boy Advance emulator under active development that also supports Game Boy and Game Boy Color games. As of yet, it's the most complete GBA emulation effort and is also available as a libretro core on RetroArch.

Hades is a recent entry in the GBA emulation, but it has a decent accuracy, speed and features. That said, while it does not have the most features in its category, it still covers the most practical as-in game controller support, key remapping, quick saves, Real Time Clock, Color correction & LCD effets and much more..!

Please note you need your own GBA BIOS to play the game.

Ares was originally Near/Byuu's last project and was subsequently continued by new developers (including Luke from Cxbx-r). That said, it's an open-source, multi-system emulator focusing mainly on accuracy and some of its exhaustive features include but are not limited to native multi-platform UI adaptive sync, dynamic rate control, save states, run-ahead, rewind or fast-forward and much more..!

Visual Boy Advance - Merge (VBA-M) is a fork of the inactive open-source emulator Visual Boy Advance. It mainly targets Game Boy, Game Boy Color and the Game Boy Advance though somewhat offers emulation for Super Game Boy and Super Game Boy 2. While supporting all previous features, it adds Link-cable emulation between GBA gamepacks, Joylink GCN/GBA emulation, e-Reader(still in development), etc. It has a very good accuracy level and is available for Windows, Linux, macOS, BeOS, GameCube and Wii. 

No$GBA is currently the fastest working GBA emulator, though not the most accurate on GBA and even less on DS. It supports multiplayer and is able to load multiple GBA/NDS ROM files for linking games.