I don’t get why Anker should try to license their magnetic charging stands for the 15w speeds. These docs normally live on your nightstand and are used between going to bed and waking up, so there is plenty of time to fill up your phone. If we then also take into account that slower charging speeds are way more healthy for the battery, the 7.5 seem to be a be a better solution.
It also does not make a lot of sense to use any kind of wireless charging when you are in a hurry. 20w over a cable have a lot more pace then 15w over MagSafe. From a pure technical point of view 15w wireless charging fills a gap that exists for a very good reason. Maybe there is some kind of increased comfort that has not opened up to me, but I don’t get it.