Most collective nouns provide a hint as to the look or behaviour of the group. You certainly can't have more fun than a barrel of monkeys. But the other two are a bit less familiar; cartload and troop. Not listed are a couple more collective nouns relative to monkeys; tribe and wilderness.

I chose a photo of Rhesus monkeys for no particular reason other than the fact they are photogenic.

Rhesus monkeys are familiar brown primates with red faces and rears. They have close-cropped hair on their heads, which accentuates their very expressive faces.

Rhesus monkeys have an important history with humans and have aided a great deal of medical and scientific research. Rhesus antigens found in their blood enabled doctors to identify the different human blood groups. These primates also preceded humans into space.

More Info: en.wikipedia.org