The most used Chinese dialect on the Web?
On the web, standard Chinese is widely used. Simplified Chinese is used by Mainland china; Traditional Chinese is used more frequently in places like Taiwan. But the two speak the same way, so it doesn't matter.

Another trend is that more and more sentences are created by young guys on the internet, and the sentences are widely spreading on the web, so that only young people often browsing Chinese language internet can know what it means. And these sentences often make old people confused.