Although the singers, who appeared as guest mentors on the show last weekend, are backing Leona Lewis to win, they do not believe that any of the participants can be compared to 2005's winner Shayne Ward.
"I've seen the odd show," band member Nicky Byrne told the Daily Record. "Leona has a great voice but, all in all, X Factor doesn't have the talent like last year when, from day one, Shayne Ward stood out as the star.
"He was good looking. He was a great singer and a good dancer. He had everything. In terms of the X Factor, he had that. I don't think this year has anyone like that."
Westlife are not the first stars to criticise X Factor after appearing on the show. Last month Rod Stewart described the performances as "rubbish" in a radio interview, while Tony Bennett complained that the series was motivated by financial greed.