Are you talking about their performances for Australia, or in general?
Because Viduka and Kewell were a few levels above Cahill at club level.
Viduka finished 3rd,3rd,4th,4th in the EPL season goal scorers during his career.
He also won Scottish player of the year after a 27 goal season for Celtic.
Remember Kewell absolutely peaked during an era where playing for Australia by European based players was regularly overlooked because of travel and Australia being in Oceania with most games against the likes of Fiji, Cook Islands, Vanuatu etc
If Kewell came through now, he'd be far and away our best player ever in G&G, the bloke was an absolute wizard in his early 20's, he was genuinely one of the best wingers in the world at Leeds. I can't explain to the younger generation who missed him, but it'd be like having someone like Mahrez or Sadio Mane play for the side now. Id argue he was better than someone like Mane though when he was peak Leeds.
Being that few years older than Cahill, his world cup appearances were also limited because of having to qualify against Iran (he couldn't of done much more than he did) and Uruguay version 1.
It's a travesty that group of players never got the current regular competition we get by being in Asia (it has it's critics, but the Asian Cup and it's qualifying process and the qualifying process for the WC against top sides, like Iran, Japan, S.Korea etc are a major step up from Oceania and the travel is usually much easier from Europe for away legs).
I'll just leave this here: