I don't know what "site mogging" is, but apparently "emsh.cat mogged simonwillison.net" with the following description:

> emsh.cat wins due to its superior use of negative space and a more intentional, minimalist typographic hierarchy that creates a sophisticated reading experience. While simonwilliam.net provides high information density, emsh.cat achieves a more polished and modern aesthetic through its refined layout and balanced composition.

So "mogged" is about minimalism somehow? Fancy/modern term for "beauty" or similar?

I think it means which site is numberwang.

Mogging is gen z alphabro/incel speak for "dominating" another that gets used ironically. If I'm taller than you, I might say "get heightmogged". This is used to absurdity, where one is able to get mogged in any number of varieties, including having the nicer website "sitemogged?"

https://knowyourmeme.com/memes/mogging