Like others already mentioned, Quiver (http://happenapps.com/#quiver http://happenapps.com/#quiver), but it is Mac-only. Your a Mac-user, but I don't know how o

Like others already mentioned, Quiver (http://happenapps.com/#quiver http://happenapps.com/#quiver), but it is Mac-only. Your a Mac-user, but I don't know how often you work with clients using another platform. That could be a problem. For Windows and Linux, there's Cherrytree (http://www.giuspen.com/cherrytree/ http://www.giuspen.com/cherrytree/). I'm not using it myself, it's just something that I found when looking for Evernote alternatives. It has syntax highlighting and can handle images. Good luck with finding a solution.