One of the most emotional fights in the series - this shows how far hiei has come as a character. From a selfish demon to one who fights to free others.
If I remember correctly this is the first real high-speed battle we saw in the entire series and it was absolutely amazing! From the choreography to the music, still brings back good memories.
When Yusuke's demon blood really kicks in and his ancestor Raizen takes over his body, we see this awesome transformation. After that, he pretty much bodied Sensui.
Me personally, most times it's with the lights off. As a matter of fact, I only turn back on the lights when I'm looking for something like the remote for instance.