I have a Otterbox case does it really make that big of a difference?
$33 from eBay, new, smart case in leather for air 2:
http://www.ebay.com/itm/Apple-Smart...ew-/222511072116?_trksid=p2385738.m2548.l4275
ROFL! Be honest...you're rolling with this, aren't you?
http://ecx.images-amazon.com/images/I/51tJxe56jzL.jpg
I've tried using Defenders in the past on an HTC One M8, a Samsung Galaxy S5, and an iPhone 6S Plus...it never worked out...ever. Those things literally double the weight and thickness of the phones AND make typing or moving or sliding or anything with regard to screen interaction a nightmare.
I'm using an iPad Pro 9.7" with the Silicon Case and the Smart Keyboard. The Pro's about a pound. I think the keyboard's about another 1/2ish pound and the Case might be 1/5 of a pound...if that. The case adds minimal thickness, feels AMAZING to hold and actually IMO makes holding the device even more comfortable because the hard, rigid curves of the metal sides get bumpers!
Try something from Apple like Anna suggested if you can.
So to answer your question...yes, absolutely, an Otterbox makes a device BALLS to use. I had a Symmetry on an iPhone 6S Plus for nearly a year and when it broke, I replaced it ($40 for the Otter @ the time) with a $10 Speck grippy thing. It's easier to hold, doesn't hurt my hand as much, doesn't slip out...IMO, Otterbox is for the guy/gal who holds their phone outside their car to take a picture while rolling down the freeway...or anyone with cats, dogs, kids, etc.