I went for the L322 as I am and always will be a Range Rover man - life without one sucks!!
I happened upon mine on a drive home from work and I just had to go and have a look - got it for a steal at just over £7k having done 137k miles.
Had a few niggles along the way, ABS Sensor, Ride Height Calibration, dicky Height Sensor, knackered locking wheel nut - that one was fun, new brake pads, new thermostat - all in the first 10 weeks of ownership....nothing that couldn't be done myself thankfully.
The GM box on the TD6 does have a habit of sudden failure, so make sure you get history with the vehicle....they are a dream to drive and so effortless....
Many don't like the look of the L322 they say it is to big with a fat arse, but when the P38 came out people said it looked to much like a Metro Cab!! - personally I think the L322 is the prestiest of the bunch.
The Classic was a design icon - timeless, the P38 brought comfort and class, the L322 dragged it into the 21st century with amazing road presence (I love driving right up behind someone at a set of lights so all they can see in the rear view mirror is the snarling front end with RANGE ROVER logo filling the rear window...)
They do have electrical niggles and throw diva fits on occasion, so get yourself a diagnostic device for it (best budget device is the RSW All Comms £200 ish).
I have driven a Disco 3 back in 2007, the company hired me one for a trip to Cardiff of all places, and it was very nice and comfortable - but I didn't get that 'Feeling' when I drive a Range Rover from it.....
We also have a 2011 Disco 4 at work, and this is pretty much the same - comfortable and pretty quick from the TDV6 engine - but when I get back into the Rangie - it just feels right...the woes of the day melt away and I can glide home knowing I have one of the best 4x4xfar....
The new models are sublime off road, the Range Rover look too big, but aslong as you remember the overhangs and ramp over angles, she'll get you any place you need to go (tyres are as always the key in most cases)....the Disco 3 and Range Rover head to head off road I would say the Disco has the edge but only just - the Disco 3 came with Terrain Repsonse - the early Rangies (02-05) didn't.....
Fuel Economy from the Rangie TD6 is in the mid twenties (Hippo will know - he has one!!) as mine is Petrol and I get average 15mpg on LPG....the Disco 3 probably won't be to far removed from the TD6 figure.
As with all Land Rovers - never buy with faults no matter what the guy selling it says, he just wants to shift it....
If you find one you do like take it on the longest test drive you can and find as many different road types as possible....I was lucky when I tested mine - the guy didn't come with me - so I took over an hour and found an A road to stretch its legs, a windy conutry lane to test steering and body roll, a rough track to test the suspension and a town highstreet to test the stop-start town driving experiance....I then found a quiet road and parked up, then went all over the vehicle pressing things, twiddling things, bonnet up with my head in alsorts of places, under it, on it, in it, all over it.....
Whichever you chose - Disco or Range Rover - you will be in for a love affair, you won't want to be without, but at the same time it will test your paitience, frustrate you and make you want to tear your hair out - but there isn't a better marque out there.....