Many people demands to create SEO friendly urls on IIS. As most of the servers doesn’t have 3rd party add-on for SEO. so making url which doesn’t have “&” “?” is not possible.
As far as Apache have mod_rewrite module installed by default on many servers. so we can able to make SEO friendly URL easily. As per our experience we have seen that Apache having many features which IIS unable to provide by default.
So I always recommend our customer to get apache server. and come top to search engines pages.