I think Dayco did a very nice job with their FAQ, Id be comfortable buying their belts.
I used a gatorback in my truck, which does not get a lot of use, and it started getting very "chirpy" this spring, after only about three years. I replaced with a gates and it is silent. Not sure if this is a negative for the gatorback, but per the FAQ, it seems like the belt should have lasted 7 years + in non-severe service. A chirping belt to me is a problematic belt.