When i was in the market for a car before i got the GSF the C63(4.0 Biturbo Saloon) was a very serious consideration for me, in fact it was my first choice before deciding on the GSF. I had done a lot of research on the C63 and came back with the conclusion that it's an amazing car with an epic engine that one would only keep within it's warranty and then move on. My priorities were to get a daily driver that i would be keeping for a very long time and one that was fairly easy to maintain. Hence the decision was easy for me (although i may have been a little biased as a previous owner of a Lexus that ran for 12 years and has never missed a beat) and since the GSF is quite rare, it is nice to have some people do double takes when they look at the car.
Following your previous thread, your decision was between the LC500 and the C63. In my opinion, between the 2 i think the LC500 looks more special inside and outside. In terms of performance, the C63S would probably take it. I love the iconic C63 (in coupe form) but if it was between the LC500 i'd take the LC and be really happy with the decision simply because it has more than enough performance for road use and it certainly looks more exotic that a C63.