Yes, a convection toaster is better than an oven toaster for toasting bagels. While some people think the two terms refer to the same thing, they are in fact two different appliances.
An oven toaster is a more advanced version of a standard pop-up toaster and comes equipped with additional features like broil and bake. By contrast, a convection oven functions just like a toaster oven but includes a fan. This fan works to circulate heat, resulting in a more even toast.
Of all types of toasters available for toasting bagels, convection ovens work the best.