I have my brother's new 2007 Tundra Double Cab 4x4 with the 5.7 engine sitting in my driveway next to my 2006 LC. The Tundra has the TRD suspension with 275/65/18 tires, standard bed, the NAV option, and a nice leather interior. The big engine with the 6-speed transmission is pretty impressive.
I cannot compare the 4WD systems, as I do not do "sport" offroading. However, my observation has been that pretty much anything with 4WD -- and even a 2WD Toyota Camry (*) -- will work for light offroading.
I would make the decision based on what and how much you need to carry. They are really two completely different vehicles. The Tundra is big, and it can haul. My brother filled it up with slate and limestone to landscape my yard and said the only difference was that it handles better with the weight. He didn't even notice the load with acceleration and braking. I didn't measure, but it looks maybe a foot or two longer than the LC (even without the long bed), which might may tight trails kind of tricky.
The Tundra's interior is a definitely generous. My brother is 6'2" and says it feels great. When I drove it it felt cavernous. The interior quality on my 2006 Landcruiser is a little better, except for the leather seats. The quality of the aftermarket leather on the Tundra is much better than the factory Toyota leather. Both interiors are very nice, though, and anybody not related to royalty should be pleased as punch sit their backside in either vehicle.
(*) I was at the Colorado 4Runner Jam several years back. We were doing a trail (?) near Leadville I think and were descending after an afternoon of fun. On the way down we passed a Toyota Camry picking its way upward on the trail. Jeff the Marmot piped up over the CB "And on your left you will notice a recent model Toyota Camry -- with a rental car sticker on the back, which indicates that even stock it is already a capable off-road vehicle." I looked as it passed and sure enough, there was a green Enterprise sticker on the bumper
