Being not particularly good at either, I can easily get as much out of the whistle as I can out of the flute.
Also, whistle causes minimal physical pain, while the flute causes several joints to hurt, and my right forearm and hand sometimes go numb when I play the higher keyed flutes.
Flutes definitely are one of the worst instruments ever in terms of ergonomics. That doesn;t stop me - I love 'em.
I am definitely a “utility whistler” - I have one in the car for learning tunes. I picked up most of the Blackbird set dance this morning on the commute. But. . . given a choice, gimme a flute every time )