The only reason I may not want Apple Care might be if I plan to sell it within a year for the next gen iPhone. That's what I did with my previous iPhone 5S. However, for this phone, I foresee myself using it for 2 years.
You can cancel AppleCare+ mid-stream. So once you sell the phone, you can call and get a pro-rated credit.
Though, if you drop your phone and make a claim through AppleCare+, then cancel later, the cost of that repair gets deducted from your refund. One drop is usually more than enough to wipe out the balance of any refund, since you'll have gotten your money's worth. So just keep that in mind.
http://support.apple.com/en-us/HT202704