Especially now that the 6+ can draw at 2+ amps I'm upgrading most of my chargers to 2a chargers. Ordered some iPad 12W chargers for my wife and I (we both have 6+s) for home.
Just make sure you get something that outputs 2.0+ amps. The regular 1 amp car chargers don't provide enough juice for the 6+ to play music over bluetooth and have GPS running at the same.
I have one from Best Buy. It's a RocketFish one that was $19.99. Great deal.