This is going to be a controversial opinion, but after having tested several expensive gaming keyboards I realized that when it comes to roping, there is no better one than this: E5 Multimedia Keyboard.
I bought mine in 2005 or 2006 for 40 PLN (about $12) and it's still working perfectly (not exactly the model shown above, mine has a numpad and less of these funky multimedia buttons on top)
The keys are working amazingly fast, you are not likely to miss any keypress with it in fast-paced situations.
Still, it's not really comfortable for typing, so I am using a secondary keyboard when I have to write some larger amounts of text.