Roads: manual; off-road: auto
(TD5s seem to be good; a lot of people keep them a long time)
I believe there was an issue with the gearboxes on the Disco 1; resolved by Disco 2.
I prefer manuals (mostly) - I've only ever owned two autos; one elderly Jaguar and my current Freelander 2.
I did a LOT of 4WD-ing in the 70s/80s, (bushfire-fighting) almost all in manuals.
When it came to the 2011 purchase, I ascertained that the 'software' which runs the 4WD/AWD system is designed primarily for the auto. In an auto "You don't burn out the clutch". In fact, my AWD Freelander 2 goes pretty much anywhere I went in the low-range Toyota Landcruisers of 'back when I was paid to drive and chase fires across-country'. (I wish I had the 9-speed!)
With the auto, off-road, you can 'creep' much more slowly than in a manual; also with the auto on the highway on cruise-control - no worries about gear-changing.
Older manuals use less fuel than same-period autos; modern autos are sometimes even 'more economical'. Manuals are more 'informative' on the test-drive; sometimes you can get by 'after a gear has died' but when an auto-box loses a gear - it's usually the whole box out of order.
It's 'horses for courses', so - what's your course?
Phideaux