Since I don't own a 357 yet, a 44 mag with 240 winchester soft points would be my choice, it's what I use in my 44 for big game back-up.
If I was forced to use a borrowed 357 I'd opt for the heaviest fastest 158gr (if not a 180 gr tmj silohuette) bullet I could find.
Of course, if Dad was feeling nice and loaned me a Dan Wesson 357 Maximum I'd feel very happy with his 180gr sp loads.
If I was stuck with a 45 cal revolver, rest assured I'd use a soft point in that too.