Which bird is the better whistler?

Trying to decide on my next bird. Getting it in a week. Which one is the better whistler? Green cheek conure or a cockatiel? I know cockatiels like to whistle a lot, my grandmother had one when I was younger. Trying to decide on which one I want.

Whats made you decide on those two species?

Not trying to be a kill joy or such, but last time it was Quaker vs. cockatiel now it is cockatiel vs. Green Cheek Conure. If we were to assume that this is the size range of the bird that you would want and from this point, perhaps, it would be better if you listed what you are looking for in a bird. Sometime it makes this process go faster by this approach.

They both whistle but one should not choose a species based on what they can do because, for one thing, nothing is guaranteed when it comes to parrots, not even their liking you.