In [4]:
from collections import Counter
cnt = Counter()
for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']:
     cnt[word] += 1
cnt


Out[4]:
Counter({'blue': 3, 'green': 1, 'red': 2})

In [5]:
cnt.most_common(1)


Out[5]:
[('blue', 3)]