Question for RIOT balance/champion design team on dashes and blinks

What is your opinion on giving a champion a dash as opposed to a blink and vice versa?

Obviously, for some cases where the champion has an active hitbox for the entirety of the ability (such as Sejuani, Shen and Gragas) using a dash as opposed to a blink is obvious, but, otherwise, how much of a difference do you tend to think giving a champion a blink as opposed to a dash makes on the power budget of an ability and how does that weigh against "better flavour" when developing a champion? (i.e. if tristana/kha zix had blinks instead of dashes, would their reset on kill need to be taken away?)

I'm just interested in some general ramblings and insight into the design process.