• Fantastic off-road abilities and general toughness
• No electronics so that it can be repaired by myself or any other bush mechanic with the simplest of tools
• Been around for a long time so that spares are available everywhere I go

Start with the notable 4x4s: BMW X5, Range Rover, Discovery, Mercedes GL, Nissan Pathfinder, Mitsubishi Pajero, Porsche Cayenne, Suzuki Grand Vitara, VW Touareg, etc. - sure they have 4x4 drive train, but that's about it. Most don't even have a diff-lock or high enough ground clearance. In addition, they are all full of electronics and complicated engines that WILL go wrong and without your Western World Mechanic un-reparable.

Old Jeep models, Mercedes M military class (even consider Unimog) or Hummer are good quality vehicles, but either too rare or too expensive, resulting in limited spare parts or knowledge available in the middle of the bush. In addition, most of them have not enough real overlanding equipment readily available to be bolted onto.

Very quickly I narrowed the possible choice down to 2 vehicles: the Land Rover Defender 110 or the Toyota Land Cruiser.

TOYOTA LAND CRUISER
http://en.wikipedia.org/wiki/Toyota_Land_Cruiser
The TLC has a massive following. Many overlanders have used this car over the last 20 years, in particular in Africa. The car is virtually indestructible and will just keep on going forever. Many spare parts are available for it as well as add-ons and other modifications.

Unfortunately, in the early 90s, the Japanese decided that luxury was important and started including a lot of "comfort" accessories in their 80s Land Cruiser series - of which most would generally break in difficult conditions. They finally put the nail in the coffin by producing a 100 series in 1998, discontinuing the traditional old Land Cruiser series. The new one has nothing of the old predecessors and is not a proper off road vehicle anymore.

Therefore most overlanders who chose to go for a TLC for their travels, go for an old 70s series or early 80s series. The advantage is that you get the "real deal" for a very low price (you can find them for less than $5,000 in decent condition). However, you are actually buying a vehicle which is now nearly 20-25 years old if not more with generally in excess of 200-400k miles on the clock. Say what you want, but at that age, you have to start worrying about a lot of things, including the whole chassis, etc.

LAND ROVER DEFENDER
http://en.wikipedia.org/wiki/Land_rover_defender
Similar to the TLC, the Defender has a cult following. It has proven itself in every terrain of the world by having been used (and still being used today) by a number of various governments' armed forces, guerrilla groups and drug dealer cartels (that's the part I take most comfort from). There are endless configuration options and modifications that can be made to the vehicle.

Similarly to the TLC, the Defender has evolved over time, mostly due to emission regulations and other similar concerns. In 1998 they stopped the production of the full non-electronic 300 Tdi and made the TD5. While completely similar generally, the ECU included in the engine is a major problem if you are stuck in the middle of the bush as it may need electronic specialized equipment to be repaired.

In 2007 Land Rover did the unthinkable and changed the interior of the Defender to make it more "comfortable" but thereby ruining the basic reason why people would buy this car. My guess is that they thought a number of Chelsea boys who wanted to look like real men may want to buy a Defender (and I have seen a few in Notting Hill with bull bar and everything, except a single drop of mud...) and they would want to roll in comfort with their "wags".

In my case, I have had significant experience in driving the Land Rover Defender 110 in difficult terrain, in particular in the Siberian Mountains in southern Russia. I also have always liked the simple construction of the car (it is still a hand made car that can be assembled and disassembled with a set of spanners) and the slightly larger volume inside vs. the Land Cruiser.  I knew I wanted to find an old non-electronic 300 Tdi, but not too old, in order not to fall into the problems similar to the 70s Land Cruiser.  It was a long search but through sheer luck someone sourced a left hand drive 300 Tdi from the Army and sold if via Neneoverland. It was one of the last 1998 models built in 203 for the Army and had been sitting on a base for the last 9 years driving a sum total of 200 miles!