The D3 is rigid & rugged. Goes like a bat out of hell, & as a timed served range rover owner, 29 years, from the classics to the L322, I'm afraid to say I prefer the D3. The drive is precision. As for the chassis. The D3 chassis is solid & strong, if not stronger than most medium sized trucks.
The range rover L322 i find lazy. You don't drive it, it takes you to where you're going. Although more refined it doesn't feel like a cage around you, & feels like a big car & tiring when you're throwing it around.
The sport, I find a waste of time. Nice to look at, but cramped inside & you can't use it as a utilty vehicle. it hasn't even got the split tailgate.
As for the original question of what chassis is superior has to be the D3 & sport. Two bolted together is better than a single.