Duck is the second best grasscourter of his generation and it shows time and time again
Agreed - Nadal is better but they're not of the same 'generation'. For me Roddick was easily the second best player at Wimbledon in 2003, 2004, 2005 and 2009...it's a shame for him that he ran into Federer on each of those occasions.
In my opinion Roddick is better than his contemporary Hewitt on the grass even though Hewitt won Wimbledon. For Hewitt it seems like peaking one year earlier made all the difference. I'd also rank Roddick above a number of other one time winners of Wimbledon such as Cash, Stich and Krajicek.
Now here's a question for you...Roddick or Ivanisevic on grass? I'm leaning towards Goran myself.