Easy Fast or Meaningful Fast
Do you wish everyone "Have an easy fast!" or "Have a meaningful fast!"?
Everyone used to always wish people "Have an easy fast", which was a nice thing to wish people. Then, some people decided that just going through the motions of fasting without any meaning was not appropriate, and that if you're going to wish a ברכה to people, you should wish them to have a meaningful fast.
I personally think that for most fasts, we should revert to "Have an easy fast". This is because of the famous saying: concern yourself with your own ruhniyut and the other's gashmiyut. Therefore, when wishing a blessing to another Jew, I care more that they should have an easy fast than having a meaningful one.
On Kippur, on the other hand, the other Jew's ability to have a meaningful fast could directly affect his gashmiyut for that year - in fact, it could even be a matter of life and death. Therefore, I think for Kippur, we should wish people, "Have an easy and meaningful fast!"