People say sakura is stronger the tsunade, i dnt think so. Tsunade not only uses her 100 healings mark to heal but also to stay young, which im sure takes alot of chakra, also people say sakura heald al the people on the battle field. Those people only had cuts and bruises naruto is the one that kept them alive, and what there were like only 50 of them there. During the pain ark tsuna not only heald people that were almost dead but kept most alive when the village got smoked.