So, I have a 10w QC 2.0 (CHOETECH) and an 18w QC 3 dual coil (Seneo) QI charger. 18w is definitely faster on my iphone X but still cant use phone at all while charging or it only maintains or slows battery depletion. I think the 18w may just penetrate my Karapax case better than the other one due to the dual coils and higher power.
As far as iPhone it can only charge max 5 watt max currently until update is released to 7.5w anyway.
But more importantly I've come to the conclusion at its current state, wireless is best used at night when in bed or when it will be idle for 15 min or more. Never for car use.
Android users may be different.
And for those that use magnet mounts in car, I was able to put my metal plate between phone and case up beside the camera lenses and still works great and doesnt affect wireless charging at home