i think comparing them in this way is unfair and fruitless. snsd have been in the industry for more than 10 years, to compare them to twice who have only been around for just over 4 years is ridiculous. its one thing to say that twice are this generation's snsd, which i think is a far more fair comparison, but to say that they are more successful than snsd, taking into consideration the breadth of snsd's career and cultural impact is foolhardy at best. comparisons like this can only be made with equal amounts of data. you cannot compare a 10-year-long career to a 4-year-long career.
there's lots of factors to take into consideration when making these comparisons, and everyone has a right to their opinion, but i am of the opinion that this comparison isn't fair and shouldn't be made lightly, if its being presented seriously.