>>535985125
If you have to ask if there's a general recommended np level you'll often get np2 as an answer but the reality is there's no universally applicable answer. Luckily you're in the NA server so you can look into what the 2 years of future nodes are like and can tell how your potential roll targets perform at various NP levels. (Chaldea App is great for this.)

Whatever you do, just remember the game isn't hard enough that you need to stress about minmaxing. Rolling for the top meta supports + servants you like is more than good enough in the vast majority of cases.