Car: With the S4 I used an Owlpad wireless charger and it is by far my favorite car mount (with or without charging). I'm still using it in one car, but I want to find something similar for my other car. I like the Owlpad because it fits different sizes and holds them snuggly but doesn't require any adjustment. If I could find a non-charging mount in this style I would be very happy. Extra points if it uses a ball mount so I can toss the windshield mount and replace it with my own.
On the bike I don't mind taking the tpu case off. Unfortunately the mount I bought on Amazon is for a One M7 and the M8 seems to be a little longer. It still fits pretty securely without the top clip but it makes me nervous. And the one I have now rattles like crazy which is terribly annoying. For the bike I want a very snug fit.
This is what I'm using now (it sucks): http://www.amazon.com/gp/product/B00CL7YBBY/
And this is the one I used for my S4 and loved: http://goo.gl/PcGAHQ