Buying a used 4x4 - recommendations?

Hi,

I'm Looking to move away from leasing cars and buy a used 4x4/SUV. Ideally want something relatively affordable to run and reliable - have been looking at the Freelander 2, VW Toureg and Audi Q5. I have given myself a £16k budget.

What age & mileage is a safe bet when looking to make this sort of purchase?

Suggestions welcome!

Thanks