For that money,
A landy 90/110 will have a lot more off road capabilities than an old range rover, however if you are only doing small amounts down farm tracks and lanes then a range rover will be suffice. You will also get more luxury from a range rover with all the leather seats and extras. However with 6 grand you could buy a nice defender for that money with leather seats and a smart interior.
However, defenders are alot more hardy that a range rover so you could quite easily just chuck a dog in the back or get all your fishing gear in without making anything a bit mucky.
So its