Your only FF option is the 5D3. You 'd be a fool to swap the 60D AF for the archaic on in the 5D2 and 6D... Just to gain a slight (1 to 1.5 stop advantage)?
I have both the 60D and the 5D3. The latter has an advantage in IQ, but the 60D is still my main travel camera.
Edit: OP looks like we posted simultaneously... Congratulations on your buy, enjoy it!