Margarito is a 147lb fighter while KT is a career 140lb Tszyu is too small for Margarito and Margarito has the perfect style to defeat KT
Margo by stoppage. Tszyu was all power and technique. He was easily swarmed and if he couldn't hurt his opponent he was done for.
Tszyu is by far the greater fighter but it would have been a stylistic nightmare for him especially if Margo laughs at his vaunted straight right. As the saying goes, styles make fights and Tony would brutalize him but, on the other hand, Kostya is the only person I see that would beat Mayweather soundly on a prime for prime basis.