I consider that all 3 extensions should be activated. Reasons below:

• If MyVariables is enabled, we could use {{userlanguagecode}} inside of {{#switch:}} to display one thing or another depending on the language a user has specified in their preferences, also {{currentuser}} to use it in interfaces (also within {{#switch:}}) and show something different to what the other see versus what others see.
• If CategorySortHeaders is enabled, even though the pages remain in the same category, we could organize them by any text placed within 2 carets (the ^ after the vertical var |, of course) instead of ordering them by a single character.
• And finally, if MagicNoCache is enabled, although it only adds __NOCACHE__ magic word, it would be very useful for pages that constantly need to display something current and where caching is unnecessary because it delays it.