http://10fastfingers.com/typing-test/english
This is my keyboard typing speed, and not the speed with a paddle or a bug key. I was using a lousy (and cheep) keyboard, and I could have done better with an IBM Selectric, I should say.
http://www.ratatype.com/learn/average-typing-speed/
Anyway, you can read and speak much faster than you send morse code by almost any means, therefore we must say that the speed is not all important. There are some advantages in slow communications.
So what WPM is most comfortable and enjoyable for you, assuming the signal report is 599/599.