Forget trying to get the "best"
You can buy the most expensive, highest performance card and it won't perform any better than a cheap card that meets DJI's specs.
For the Phantom 3 DJI specify: Supported SD Card Types
Micro SD Max capacity: 64 GB. Class 10 or UHS-1 rating required
Use multiple 8 gig class 10 cards.
Its cheap and its much better to cycle through the card rather than having all your eggs in one basket.
Attach some to your remote incase you forget.