One show that comes to mind is Parks and Recreation. The first season was kind of rough and felt like it was trying to find its identity, but once it hit its stride in season two, it just became a powerhouse of character development and hilarious moments. Leslie Knope, played by Amy Poehler, grows so much, and the ensemble cast really shines.
Another one is Brooklyn Nine-Nine. I remember thinking the pilot was decent but not amazing, but once they fleshed out the characters, it became one of my favorite comedies. The chemistry between Andy Samberg and the rest of the cast just kept getting better.
Have you checked out either of those? What kind of genres are you leaning toward for your hidden gems?