What affects power more in a camshaft....high lift or longer duration?

Higher lift isn't hugely advantageous if the head doesn't flow well at the additional extension. But, I think there is something to be said for having lift above peak flow though. Air doesn't move instantaneously so the additional lift probably helps the system flow better by carrying the valve above the peak flow point.

Kern Dog said

The old style Mopar Performance cams always seemed to be long on duration and short on lift compared to other brands. Conversely, the Hughes cams are the opposite.

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My impression is that the low lift long duration combo of the Mopar cams was to accommodate the stock iron heads which were lift limited without additional machine work/parts. They could be made to handle high lift, but it took machining time and parts which equals $$$. The easier/cheaper way to increase airflow through the head and thus performance, was with longer duration. It's a compromise solution, but they probably sold a lot more cams that way.