There are hardcore supporters of the idea that "full frame is always better. " I do not think so, and choose 70D without hesitation. Weather sealed, AFMA, AF far superior, more images per second, higher resolution, LCD infinitely better, etc... I have not used original 5D, but some friends use and the noise in the shadows is very ugly. Any Rebel model currently has more like colored noise film, while the original 5D has horrible colored spots.
I'd pick a 70D over a 5D any day of the week. With a 5D2, there would be a lot of humming and hawing and then I'd get the 5D2. The 5D2 is a major improvement over the 5D... heck, a T5i is an improvement over the 5D.
to go from a 5D to a 5D2 changes:
from 12 to 21 megapixels
max ISO from 3200 to 25,600
both with 9 focus points
a larger screen with 4 times the number of pixels
an impossible to find battery to the LP-E6 that seems to be in everything now....
you get video
you get live view
you get sensor cleaning