How to Setup Resolution and Frame Rate Between Two Cameras for Premiere Editting and YouTube
1080P/24 seems to be the way to go in this case.  It's generally considered to have a more cinematic look and both cameras appear to support that resolution and framerate.  Youtube has a 24 fps setting and should handle 1080P video fine.  As you already said, use All I on your 70D to ensure highest quality.