I have previously owned a 2010 L322 (mkIII 5.0) as well as a 2008 L322 (mkII 4.4).
With that being said I currently have a 2006 LR3 4.4 and a 2010 RR Sport 5.0.
I have owned 28 land rovers in total... 2x L322, 8x LR3, 6x D2, 4x D1, 5x RRC, 2x RR Sport, 1x D90 and worked for LR dealerships for 10 years
I can tell you a few things about the L322... They're the same chassis from 2003-2012. The upgrades in the 2010+ and extra 85hp of the 5.0 is well worth the money but the 4.4 is basically bullet proof.
On the other hand... DO NOT BUY A 2003-2006. Steering column lock failure will cost more to fix than the car is worth and the BMW electronics are terrible!
All have a few inherent issues....
1) Front air springs go bad... Do not buy replacements from Arnott. Bags are replaceable separate from the strut assembly and are available from LR or Dunlop for around $350 each in parts
2) EAS compressor mufflers get clogged with moisture... also available separate front he compressor assembly but can be alleviated by drilling a hole (1/4") in the muffler. The EAS code reads C1A13 - Pressure does not decrease when venting galley
3) 5.0 timing chain tensioners - there are a million threads on this. Don't prolong it - bite the bullet and get it done. Mine were $2800 at a LR Indy (Make sure they replace the water pump during that service) Injectors and HPFP are also a known issue of the 5.0. Injectors are available from Bosch for $100 ea.
4) Maintaining the 5.0 is easier. No lift required for an oil change... Buy a fluid extractor from harbor freight and do it yourself for about $80
5) LR recommends Trans Fluid at 150k, T case and Diffs at 75k, oil changes every 15k (5.0, Synthetic) and 7500 (4.4, Conventional). I change my oil every 7500 in both. Lots of people see oil consumption with synthetic in 4.4, just use the recommended non syn)
6) 06-09 Supercharger Aux. water pumps fail with some level of frequency and the 5.0 Supercharged motors just cost more to do anything. I would avoid either unless you're just addicted to HP.
7) Lux Pkg cars have heated and cooled seats. The peltier elements will go bad frequently halting the operation of the heated and cooled seats. Nice feature but the design lacks and expensive to repair.
I LOVED both of mine.. Wish I never sold either of them but I suffer from chasing the next shiny thing. The ride quality and street presence is second to none, also took them both off road and performed flawlessly.