Cups is the suit most readers find easiest, and the ease is worth examining because it can be misleading.
The Golden Dawn assigned the suit the element water and the emotional and relational sphere, and modern practice has followed that so completely that Cups and feelings are now effectively synonymous. In older cartomancy the suit was read rather more broadly, for friendship, hospitality, favours, social standing and the church, alongside love, and the narrowing to inner emotional life is a twentieth-century development that tracks a wider cultural shift, not a discovery about the cards.
That narrowing costs something. A suit that once covered a person's whole social position now often gets read as their mood, and a spread full of Cups is taken to mean the querent is being emotional when it may mean they are embedded in a web of obligations and relationships that is doing the actual work in their situation.
The suit's numbered cards in the Rider-Waite-Smith deck are also the most sentimentally drawn, and several of them, children in a garden, a wedding party, a figure gazing at a cup, carry a Victorian sweetness that can flatten a reading if taken at face value. The harder Cups cards, the four and the five and the eight, are the ones that keep the suit honest.
Read at its best, the suit describes what a person is attached to, which is a larger and more consequential category than what they feel. Attachments have obligations attached to them, and the suit's harder cards are almost all about the cost of that.