If it/this/that is not..., I don't know what is.
如果XX都不算...,我就不知道什么算是了。
If someone is not..., I don't know who is.
如果XX(某人)都不算...,我就不知道谁是了。
如果这都不是城里最好的饭店,我不知道还有哪家是了。
If this isn't the best restaurant in town, I don't know what is.
如果哪都不算浪费钱,我不知道什么算浪费钱了。
If that is not a waste of money, I don't know what is.
如果胡歌都不算帅,我就不知道谁帅了。
If Hu Ge isn't handsome, I don't know who is.