I originally was more leaning e70 than e53 but a couple friends pointed out a few things.

"you know that n52 you hated so much in your X3? The 3.0 e70 has the same one"

"Turbos..."

"There's a whole set of extra electrical issues in the early models than the e53. More advanced and integrated electronics"

I looked around at quite a few options that were in my price range (read: cheap, less than 5k") and they all seemed to have similar issues: The engine would randomly shut off, blown motors, issues with the DSC electronics and everyone's favorite grab bag of error codes and lights.

After a little bit of soul searching and asking myself why would I want to do this to myself I realized what I was really looking for was essentially a more modern audio/gps features (which the e70 is only slightly more updated) and I liked the more modern interior.

I did initially prefer the look of the e70 but again after really thinking about it...I just like how the exhaust is integrated more into the bumper than on the e53. That's the only part of the e53 I don't like at all...exhaust.

So basically I wanted a slightly "newer" looking interior and a fancier radio. The radio I can do 1000% times better by going aftermarket and dealing with that on the e53 will be significantly easier.

I LOVE the m54 platform and it has proven to be a rock solid platform for me, not so much my first experience with the n52 ($600 water pump around these parts) so I went with the e53.

Also, I'm pretty sure the e70 has slightly less cargo space, which was a crucial factor for me coming up from an e83.