I’ve been using Quiver for a few years, and love it. Totally replaced Evernote for me. Not sure if they have syntax highlighting though — there is a “code” cell, but I haven’t used it.
I also use Quiver, I just wish I could have my notes on my Android phone. No one has yet brought together quite everything -- there's always tradeoffs between the various note apps, even though there doesn't have to be.
http://happenapps.com