What do you consider as Staples for competitive deck building/play?
What are considered to be deck building Staples?
You can browse winning decklists on thronesdb or whitebookpodcast to get a sense of what cards are often included. The answer to your question will vary depending on Faction, but with the currently small card pool, almost every "good" card is a staple.
Noble Cause, Summons, Wildfire, Littlefinger, Varys, Roseroad, Kingsroad, Milk, Seal, Tears and Sword are some of the more popular neutral cards.
I would add The HAnd's Judgement to that list. Every faction has at least 1 event that is painful, and the neutral eventsthemselves can be painful if they catch you at the right moment. The Hand's Judgement takes the worry out of games.