Ishiiruka is a fork of Dolphin Emulator which adds a few more graphical options such as material maps, advanced shaders and various other tweaks. Ishiiruka runs on a much older build of Dolphin Emulator so it will not have some of the more up to date features.

Some users find they get better performance on Ishiiruka however overall it appears the majority of users get better performance on the later/regular builds of Dolphin.

PrimeHack is also offered on Ishiiruka: https://github.com/shiiion/Ishiiruka/releases

You can make the PrimeHack Updater download Ishiiruka instead by editing updater.cfg and setting mainbranch to False