I've got 2 cases for my 6 which Ive had since launch.....
Mophie Juice pack plus (rechargeable) protects the case absolutely fantastic as well as being able to charge the phone by up to 120%
Spigen tough armour.....Slim, looks good, and protects the iPhone better than any case I've ever used. Covers all edges, minimum amount of dust gathers in the case. It's kept my phone looking new and thats been since launch.
Them along with a glass screen protector, can't recommend these enough.