We are getting near end-of-life on our 2005 X5 4.8is (e53) so we just bought a 2008 X5 4.8i sport (e70) that came up sort of locally and through the BMW club. Well kept and reasonable miles/price. We didn't want to get the turbos (had a 2013 X5 5.0 for 45k miles) so stayed in the pre-turbo years. That means we may give up some MPG.

We will keep the old one for use with the dog and as an extra winter beast until it gives up the ghost.

Was also considering an X5M but much more costly to buy and keep, and I have an M3 for the serious driving fun!

Obviously what you choose to replace yours with depends on your needs, desires and budget.