All valid points Elsa made. Gonna play a big role in your decision. Also your budget. Maybe you wanna consider sticking to Nikon, seeing that you are familiar with the menu layout and now that you already have I assume a lens or two that you could use on your new Nikon body.
As for going over to Canon, good cameras for both stills and video would be the 70D, 77D or the 80D. And you are correct in saying that there is more to choose from when it comes to Canon, especially in the secondhand market.