He's good. Who do you think is his best competitor?
I think his best competitor is Rafael Nadal. A close second is Roger Federer. 
Both tough players and successful in their careers. You ever see a live match with any of them?
Yes I have. I watch them and take notes in order to do better in my own play. 
Who do you think is the better player Rafael Nadal or Roger Federer?
I think Nadal is the better player, but it's really close. Nadal is real popular here in California, but Isner is still my favorite. 
What is it about Isner that makes him your favorite? He has been beat by others, such as Reilly Opelka
I like his powerful serve. That is how I want to serve. 
Serving gives one a big advantage initially. Do you think the speed of the sever is more important than the type of spin or trajectory?
I think speed is the most important.