User blog comment:Sarah Manley/A Facelift for the Edit Page/@comment-1338091-20110414043809/@comment-13301-20110414094014

Think that Monobook is part of the standard MediaWiki installation, while Oasis is only maintained by Wikia, like Monaco. Oasis would be dropped (and replaced by another new shiny skin) before than Monobook, as happened with Monaco, so your customizations would last longer in Monobook than Oasis. Think about Oasis as a transient skin.