If you get the defender you're really getting it for the look unless you end up getting a longer 110" or a manual transmission.
They both offer about the same engines, solid axles, and terrain response systems. My recommendation would be to look for a '04 Disco. This one was the last year they were made and came standard with a central locking diff. The one thing that makes a huge difference to me though is that the interior of a Discovery is outrageously better by getting more space, heated seats, heated front windscreen, sunroof...
True story, a guy in the local rover club had one of the coolest 110" Defenders and ended up selling it for a LR3. The reason was that after taking a trip to AZ in the defender his wife said enough of this after having to endure with the smell of diesel, road noise, and no ventilation from the horizontally opening side windows.