In my household we have a 2000 E46 that has been completely restored and is just one of those cars that would be hard to part with because of its history with me, also a 2012 E70 X5 sport, and the 2003 E53 3.0. I personally still much prefer the look and driving feel of the E53 over the E70. Sure the E70 looks mean with its wide tires on its 20" sport wheels, but there is just a feel that the older BMWs have that just isn't present in the newer ones. Even though I've been chasing down a terrible electric gremlin in my E53 for the past few months I still get a big smile on my face when I drive it. Same with my E46. I've been behind the wheel of all of the newer model 3 series cars and they can't even come close to producing the road feel of that E46. I'm sure at some point my E53 will become at its point of needing to move on, but I would be more inclined to look for a newer E53 sport next time to replace it.

I say keep the E53 and drive it until the wheels start to fall off. They just have character that a true BMW enthusiast will always appreciate.