Depends entirely on their interests and story preferences. What genres do they like? Do they love or hate romance/fantasy/superheroes/vampires? Would they prefer a teenage MC over an adult MC or vice versa? What books/shows are they into? CoG offers a wide variety of games but what some players appreciate, others might detest with a passion.
Some pointers:
Superhero fan? Psy High (if a high school setting is preferred) or Heroes Rise (for that comic book feel). (Fallen Hero is my personal favorite BUT: The series isn’t finished and those two other titles might be a better fit for a CoG newbie, especially if they are looking for stories with more heroic, less ambivalent MCs.) Vampire romance fan? Wayhaven. The Expanse fan? Asteroid Run. Sherlock Holmes fan? A Study in Steampunk. Wrestling fan? Slammed. History nerd? Choice of Alexandria.
General recommendation if romance is desired without fantasy elements: Crème de la Crème.
Depending on whether you/they want to research more titles on your/their own, maybe consider having a look at @BourbonDingo’s insightful game reviews over here.