The LS400 is without a doubt one of the best cars available for little money, I've had two so I can speak from experience. The LS430 is in my opinion a much better looking car. When scrubbed up they really look the business. The cabin is superb, the gadgets will keep you amused in traffic jams, and the wood veneer is like being in an antique shop! As I've said before, we tend only to hear about the ones with problems, not the ones that go on for 200K without issues.
However, If I was to do a very long drive, like across Europe for instance, and I had the choice, I would probably do it in an LS400. Seven years of ownership and I spent less in those years than I've spent on the LS430 in 6 months.......but I still think it's a fab car that's ridiculously cheap for what you get.