I dont' own either a Land Cruiser 100 or a Sequoia, but got some wheel time behind both (a 2001 100 and a 2005 Sequoia). I think in stock form, both are good as a daily driver, weekend warrior rig.
The Sequoia surprised me in that's fairly big and roomy compared to other rigs and seems well built. However, the 100 series is at a whole different level when it comes to overall strength, including chassis and suspension strength. This is especially critical when it comes to overloading the vehicle with modifications and gear.
What worries me about the Sequoia is that I wouldn't trust it's front end or steering for extremely duty and I wouldn't trust its frame to be able to withstand being overloaded. As any expedition hauler knows, by the time you've added a front bumper winch, some armor, sliders and a little bit of gear, you're at the max vehicle weight limit, so it's very common for most of us to exceed GVW and we want a vehicle that has been proven to be able to not only withstand exceeding GVW, but doing it while traveling off road.
The 100 is about 300-400 heavier in bone stone form than the Sequoia despite being somewhat smaller in size. It puts the "heavy" in heavy duty. The Sequoia may technically have slightly greater payload capacity depending on which spec you read, but the Land Cruiser has been proven to be able to be well overloaded with no issues. The Sequoia hasn't been proven to accept excess weight to my knowledge, but then it's not commonly used for that purpose.
If you don't plan on building up the rig or adding signficant weight to it, I think the sequoia will do great.
My other opinions are that the Sequoia "appears" to get better gas mileage. My brother in law claims that his 2005 has gotten close to 20 mpg on long trips, with the V-8. I find that hard to believe, but in any case he's achieving better than most 100 series.
One nice thing about the Sequoia is that for less money than a 2005 or later 100, you can find a 2005 or later Sequoia and still get the same updated V-8 engine, making more power and the new 5 speed automatic tranny.
In my opinion, it all comes down to whether you need light (or maybe medium) duty or heavy duty. The Sequoia would make a great cost effective option against the 100 for rig that needs to do double duty as a daily driver or kid hauler on the weekdays and take the family out on weekend jaunts or even long road trips. But if you're trips involve fairly remote travel, especially if we're talking adding a lot of weight and anything that would put a lot of stress on parts like the suspension and especially the front end, I'd definately move over to the 100 series.
Now I'm only comparing the Sequoia to the 100. If you compare the Sequoia to other non-Toyota SUV rigs, the Sequoia could be the superior vehicle, but then I'm pretty bias.