I used Gates belts on snowmobiles and other applications like cars they seem good. Every Gates snowmobile belt lasted me over three years because I don't take off like a wild man on a snowmobile and on cars much longer than 5 years. Price is the one thing for you to think about because cheap sometimes is cheap, so which of those belts is the more expensive? If it costs more to produce then it will last longer in my opinion.
I have yet to buy a spare belt for my 2017 450,however when I do it will be a Gates of a Carlisle belt.