I have owned a Thule Evolution 2100 and the Yakima Skybox (both 21 cubic feet). They both fit okay on the LR3, though they do extend forward of the windshield a bit...or at least over the sunroof.
The quality is about the same, I think the Skybox has slightly better locks. The lid on the Thule was lighter, and it was slightly easier to handle when it's not on the truck.
They were both very quiet on the road, the Thule rack mount was a little more secure fore and aft, but the box slid side to side on occassion. The Skybox mounts differently, and requires a bit of tension for good fore and aft clamping, but does not slide side to side at all due to rubberised clamps.
The finish on my skybox is definately a cool looking texture/pattern, and seems slightly more scratch resistant than the silvery Thule I had.
I sold the Thule because it did not fit my wife's Nissan Armada (the distance between the roof cross bars exceeded it's span between the clamps). The Skybox is definately more veratile and can span considerable distances between the clamps. So if you have two vehicles that might possibly use this box, give that some thought. My Thule fit a Mitsu Montero, Volvo V70, and LR3 fine, but only the Skybox fit the Armada.
These are big boxes, but very handy when you need them!