I had the same dilemma except I was paying out of my pocket. I went with the class 4 shingle. Went with the Certainteed Northgate. Around here I would say the roofers use 50% OC Duration, 30% GAF and 20% other.
I figured if the class 4 shingles save me from having to submit a home insurance claim in the 3-4 years it takes for an ROI, it was worth it to me. Didn't care about the warranty, I won't be in this house in 5 years. Those house insurance claims still with you for a while.