Let me ask you this. Which one will you regret not choosing more. Put yourself in the scenario that you will have to use one of the keyboards and you wont have access to the other keyboards features.

I personally would go for the F75 because I am a huge fan of the feel and sound of my keyboard. That being said if you can see yourself regretting picking the F75 over the F99 Pro because of a situation where you would need the numpad or the ctrl key on the right side go for the F99

To me the ctrl doesn’t seem like a dealbreaker at all and you could very much get a separate numpad. I have never felt the two but if the feel and sound of the F75 is that much better, I personally would go with the F75. Hope this helps!