They are both equally good though i admit i havent played all their games yet.
I will point out that ND have made a variety of genres ranging from pure platform (crash) to action adventure with hugely greater realism and a focus on TPS over 3 consoles. SSM has only worked on the single IP with similar play styles (most recent game excluded). Food for thought no?
Sony Santa Monica has incubated team and helped with development and produced far more games than ND, Journey, Order 1886, Fat princess adventures etc, majority of Xdev team are from SSM, Unfortunately they had to cancel their new Sc-Fi shooter, coz it was turning out similar to Destiny, Right now ND pedigree is excellent writing and production values, but not so good gameplay mechanics, with GoW SSM proved they can give an ND level story with equally deep gameplay.. took me 30 hrs to finish it.