Both have handled my returns without question, so I'd be curious to hear stories of how one was "hands down" better than the other.

I purchased M/T slicks from Summit that ended up being defective (one was so out of round it almost shook my fillings out). Didn't figure out they were defective until I got to the Mopar Nats and made a time trial on Friday. Summit said "when you get home Sunday, take them off and send them back". I had new Hoosiers at my door before I even had the M/Ts off.

What was the defect and which brand of tire?