Overall favorite? And remember, my perspective is different, because its more about what was fun to write, and that was when NC and Lorenzo finally meet in II, and have a good old fashioned knife fight and slugfest.
Okay, I'm biased, but I think my favorite scene I did was in book II, with Carl in the desert after the big heist. (ain't gonna say what happened, because some folks here might not have read II yet). That one choked me up.
My favorite scene from NC has to be when he executes the auctioneer, and beats the "don't you know who I am?" guy. He had already told me what was coming, but it gave me shivers. That is the first time that Valentine loses it.
The best scene ever will be in Book III, when the time machine malfunctions, and NC has to save the princess from the dinosaur people, while Lorenzo is being DNA tested to see if he is Anna Nicole's baby daddy, only to be interupted by the terrorist group CAREBEAR and their rainbow-love puff bomb.
Just kidding. Lorenzo has way too much pride for that.