The Discovery 1 & 2 both have their pros and cons.
When it comes to corrosion the Discovery 1 Chassis is normally quite good but the body work suffers, especially around the inner and outer sills, wheel arches and boot floor, though repairable they can build up in cost for a garage to do the work, as it is in my case. Engines are reliable and quite easy to work on as long as serving is carried out (oil change I tend to do every six months).
Discovery 2, the body seems to very good at not rusting, but the chassis can suffer especially at the rear. Again engines are good though a lot more electrics, though can usually be diagnosed with a diagnose kit like the Hawkeye or Britpart Lynx system. I think parts tend to be a bit more costly to. The engine though is much more refined and smother with its 5th cylinder (diesel model).
I have has my 1997 Discovery 1 Auto now for 9 years, and been pretty good. Has had a few mechanical break downs over the years (sort of things that can happen to any car) and has had a lot of welding over my ownership, especially this year with having both sills replaced, not to mention a 2nd hand auto gearbox and 2nd hand turbo to. Just can't seem to part with it