Gates belts are quality belts here in Finland, as I have read the local scooterforums for example. A bit more expensive, too. So I would recommend the quality of them. Price level for example for Like 50 is regular belt 28 €, and "plus" with iridium? in it is 36 €. And you can expect lasting like 10 000 km and longer, lets say 15000 km,depends time also I think.
So my choice is definetly Gates, when the time comes. I have now 14500 km and 9 years with genuine belt, told by previosly owner, but he was not "sure" as always when you ask.