I think the main balance problem with QSS and Hourglass is...

... that they are statbound to either AD or AP OR Armor or MR.

There are times you really would want a Zhonia-active, but the enemy is AP. And sometimes you really wished you had that QSS active, but WOOPS, the enemy is AD.

But what if... those items were no longer bound to these stats? The sole reason they are bound like this is because of how lol had been in season 1. The 99% of all champs back then that had dangerous cc dealt magic damage, so QSS gave MR. Howver, that no longer applies today.

For example, the hourglass effect is the ultimate defense effect, so I'd rather see this item have either health, or Armor+MR. And if you still want that the item is primarely build for mages, simply add something like this: After stasis, next ability deals +X damage. Or Maybe even: during stasis your cooldowns are lowered by 2 seconds. Would fit, because that's why mages originally use it: to have some more safety until their abilities are up again.

The QSS ability is a bit more offensive and should not even have defensive stats. Find a way to make it appealing to both AD and AP somehow and we finally can end this "muh your mercurial is too strong - NOOO but your hourglass active so OP, we need that!" argument that has been going on for more than 5 years now...