Who is the best colorectal surgeon in sydney for cancer?

"Best" = Subjective. I have no idea about sydney. But "best" is subjective, even when evaluated in an "objective" systematic fashion. Technically best surgical technique? Difficult to assess. Best outcomes - more objective data, but may be biased by patient selection. Best bedside manner? Most publications? Most well known? Best from a hospital (revenue generation) standpoint? Ask around, but realize caveats.
Check. Look t the international fellows on the american society of colon and rectal surgeons website.