Ah, sorry I thought your reply was in response to a different thread I made.

Yep, if that's what works for you then that's fine. I only need the skip function since I don't pause the music and mute it turning the volume dial down instead. Using Google Now isn't that much of a hassle since I just need to turn on the phone and swipe up, and OK Google works when music is playing too.

It's just that right now I don't have a Qi charger in my car or NFC tags, though I want to get some in the future. Using charging as a trigger for BT is a good idea, but I think that it doesn't match every situation that well.

This USB BT streamer turns on automatically since it doesn't have an on/off button or battery.

The main benefit of the BT FM transmitters would be less wires, and reception should be good since you have a custom channel and there shouldn't be any interference. It seems like it works really well according to the reviews, but I don't have any experience with using them. I just bought the USB BT and dual USB car charger so I won't get it.