I hope the best living sci-fi author is either still in diapers or flipping burgers somewhere anxiously hoping someone will
finally accept their manuscript. That way, there's always room for improvement.
But in the spirit of the thread...
I have a great respect for Richard K. Morgan and Peter F. Hamilton's stuff.
As for relatively new authors, I'll go with: Paolo Bacigalupi, Hannu Rajaniemi, Will McIntosh