Upade - The following might not be the "best accessories" but I hope they will help in some way or form
1) Arealer Storage Case for Samsung Gear VR & Other Virtual Reality Headset -
Amazon.ca
Looks like a cool case to carry your Gear VR AND additional pouch for cables such as usb cable, earbuds, etc.
2) YORKING™ Universal Portable Wireless Bluetooth Remote Controller Gamepad For 3D VR -
Amazon.com
Credit to VR Heads poster RumoredNow. He provided a mini review in the
following post.
3) Samsung Gear Real 360 -
Amazon.ca