For me, Geese everytime.
Swans....poofs!
On a similar subject, i saw a documentary once about a Jaguar (the animal not the car or plane) in South America.
A VERY intelligent animal indeed.
Anyway, this Jaguar was doing it`s normal jungly thing when it saw a huge crocodile/aligator/kaman (?) (what-ever it is you get in South america??) lying in a stream.
This Jaguar gave it a wide birth at first, sussed the situation out, approached the croc from behind, jumped in the water & killed it with one powerful bite to the back of the head, puncturing it`s skull.......it was a truly awsome piece of film footage!