We tried to strike a balance between "commonly accepted as fast" terminal emulators and coverage of "commonly used" terminal emulators. Termite gets us libvte-based terminals (like gnome-terminal), urxvt is generally considered as one of the fastest, and Kitty is another well-regarded GPU-accelerated terminal emulator. On macOS, there's not nearly as many choices.
Ultimately, it would be great if we could benchmark against every terminal emulator, but that can become a very time-consuming task. If there's another emulator you feel should be included, we can consider it for future updates/benchmarks.