If you uncheck "Automatically sync new apps" can't you then control what's put on? If you don't want a specific app on your phone, either mouse over it in the home screen view that pops up in iTunes and hit the X (this can be a little buggy) or find it in the list on the left and hit Remove.
Once automatic syncing is off, apps will only be added if you add them directly, which I think is what you want. Also make sure that you've also disabled automatic download on your device in the "iTunes & App Stores" settings.
It appears app syncing is now manual. I was afraid at first that without the check box I was going to lose all the apps on my phone so I transferred apps just to be safe but when I synced other stuff the apps were never affected