Nightwatch came first. I just agree with sam that Daywatch had a more cohesive narrative. And as far as awe, my favorite moment from both films is the scene in Daywatch where the woman drives her sports car across the side of the hotel. Plus, there's that totally original apocalypse at the climax of Daywatch.
It was supposed to be a trilogy, and I've heard conflicting reasons as to why it didn't happen. From what I can gather, the 3rd book in the series dealt with the lavish party and the apocalypse. During the making of Daywatch, the director was being heavily courted by Hollywood and he was anxious to bring his style to America, so he folded his trilogy into a lengthy 2nd movie in order to finish the main narrative out.