Both the original versions and the Remastered edits are canon since the stories didn't change at all in either incarnation of each episode. The only arguable exception might be the Klingon "scout ship" in "Friday's Child" which is just an amorphous glowing shape in the original 1967 version but in the Remastered edition is clearly a D7 seen from a distance. Definitely not a scout ship unless the Klingon Empire assigned some of its most powerful and advanced warships to scout duty in backwater star systems where the local natives didn't have space travel capabilities.
Or the Enterprise's sensors absolutely sucked and couldn't tell the difference even within visual distance.