No language is better than any other for seo. The primary difference between each page, as far as client side is whether the extension is php, aspx, or html. They all do the same thing, they all create html output. SEO is based on content, links, referral links, and popularity. Depending upon the site, it could be more SEO friendly with url rewriting, which they all can do. Its all a preference of how you want to write the site, and since they produce the same output, you leverage the client on server technology to use based upon your needs for the site.