Pick largest value from each groupby group pandas

Question

Here is dataframe

df1=pd.DataFrame({'precision':[70,69,69,62,73,78],
                 'recall':[80,79,69,62,76,67],
                 'f1':[73,69,69,82,73,87],
                 'clf':['ann','svm','knn','svm','ann','knn'],
                 'region':['A','A','A','B','B','B']})

I want to group region and in each region i want to find which classifier has highest f1-score and print that row. But i am not sure how to do this