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

So, if buying rocker arms for a new combination, get as much ratio as possible?
(One of the reasons bbc and LS make good power!)
Not necessarily. Needs to be a balance. Higher rocker ratio increases lift but also increases valve speed and theoretically, stress on the rocker pivot because of the shorter lever arm takes more pressure to lift the valve. Faster valve speed may require a different spring to control it. If the cam already has an aggressive lobe, the higher ratio is only going to exacerbate that. Could make for jerky unstable valvetrain, or require maintenance on a tighter timeline. I'd take the advice of the cam grinder who should know what his lobe can do.

If I was starting from scratch, I'd probably try to use a 1.5 rocker and let the cam lobe determine the lift. With a roller cam, I don't think there is much of a downside to that approach.