I got the Incipio Dual Pro to use for now -- it feels very smooth and offers good protection while still being slim. The grip is good but its not very grippy -- more like a smooth texture.. though it has much more grip than a hard plastic case.
Incipio DualPro is the best of 3 iPhone 6 cases I've tried.
Protection looks to be very good, looks good and the grip is perfect.
Just picked up a pelican protector for my plus. I've used otterbox defenders for my 4 and my 5. It's not as grippy as the rubber on the defender but it's much grippier than naked. Adds very little bulk also.