2nd serve....Pete Sampras.
For first serve, I like Ivanisevic. Nice power. Lefty. Still, if I was going to Frankenstein up a tennis player, I'd pick a guy like Ivo Karlovic or John Inser for sheer power and their height creates crazy angles. But I like your call with Goran.
Can't go wrong with Federer for forehand. I would take Del Potro's.
Murray is a strange choice for backhand. I would take Federer, Djokovic from current players. But Jimmy Connors backhand was a thing of beauty. His best shot for sure. I don't think Andy Murray would be in my top 20 choices here.
Stefon Edberg had flawless volleys. The best the game has ever seen. By a long shot. Especially his backhand volley. Having anyone but Edberg for either volley spot seems like a crime. Boris Becker or Patrick Rafter would be up there as well.
Can't argue with Nadal's stamina. I think he is the best conditioned athlete to ever play the game. Nole would be up there too but I like your pick.
Consistency favors the clay court pushers. I'm thinking Michael Chang, Gustavo Kuerten, Mats Willander....but to me, the most consistent player would be Miloslav Mecir. I wouldn't put Connors anywhere near that list.
Style...yes, Federer certainly has the prettiest game ever.
Court coverage....can't argue with Nole. Rafa is a great mover too, but Nole is crazy quick.
Can't argue with Agassi on the return game either. Connors was the best, until Agassi showed the world what a pure returner really was.
I like Monfils athletic overhead. I'd probably stick with Sampras just on pure fundamentals and he was the first guy i think of when I think of jumping overhead.
Can't argue with Rafa on the mental aspect either.