All three of these say they're 'easy' to install. Personally, I find Wikibase a bit harder than the other two. I'm not really sure how to qualify that here though. I think it depends on what you're used to, with regard to extension installation. If you have a basic wiki, and install SMW or Cargo, nothing much changes until you start editing properties, templates etc.; but if you install Wikibase (although I've never run it in production, so I maybe shouldn't be commenting) there are often extra configuration steps required, and backwards-compatibility is not supported (which is totally fine, of course, but for your average non-professional wiki sysadmin can make things more complicated).
Could we say Wikibase has 'medium' installation difficulty?