I used to use Evernote before it stopped being good and keep kicking you off your devices after the 2nd one. New Notes app on OSX is actually pretty good now, just change the silly font it comes with something normal. It syncs to iCloud on mac and iPhone and across all your Apple devices. It does merges incredibly well. I remember Evernote every now and then would duplicate ton of my notes because it couldn't resolve a merge conflict, this has never happened on Notes. Give it a go!