A heron with a nice brookie. Reference image from Creative Commons. Watercolour, I am currently painting a version in acrylics.
So far acrylics are agreeing with me better than oils, but watercolour is definitely my first choice.
I do have to put in a plug for CC image searches. Lots of great photos out there with attribution licenses. A great boon for those of us who are not professional photographers with unlimited budgets for travel and equipment.