?? 5D or 5D MII ??
I had both - sold 5d some time ago to keep mark II, and now bought the old 5d again (great deal, mint) and just about to sell mark II. Partly because I need cash but I can't really see any serious advantages of mark II that would make me keep it. I love hi res screen, live view is sometimes useful, but I don't really mind the rest. And I never liked the 21mp - far too much for me (storage!!! I shoot a lot and only in RAW). In terms of picture quality I prefer more detailed (on 100% level) and natural picture from the old 5d, I also find PP a bit easier, but that's all subjective. AF, ISO (up to 3200), handling - it's all the same. I also kinda "love" the old 5d, it's a legend and I've learned so much about the photography with that camera.
If I could afford it - I would keep both-- hide signature --
I wonder if you got my old 5D (which was mint, 4500 shots). If I had it to do over again I should have skipped a generation. But I do like the 5DII. It will take some time to learn it's strength and weaknesses.