Either will work fine as a porter should have no appreciable hop aroma and minimal flavor hops. I would use the sterling and a fair amount of specialty grains for bitterness. My favorite hops for porters are the cheaper UK varieties such as challenger, target and brambling cross. US substitutes that work well are US Perle, Northern Brewer, Willamette and US Fuggles. UK Fuggles and EKG are excellent of course, but generally wasted on a porter.