The vastus medialis (teardrop) is one of the most common body parts that lags for people, probably a close second to calves. Here are 3 key exercises to help you develop them:
(1) Skater Lunges - Standing upright with a shoulder-width stance, step your right leg behind and across your left leg about a shoulder's distance away. Then squat down by bending both legs and touch the floor with your right hand (assuming you are not holding dumbbells). Then switch.
(2) Bulgarian Split Squat - Set up a bench behind you, curl one of your legs and place the top of that foot on the bench. Once in a comfortably balanced position squat down to where your knee just touches the ground. With your front leg, make sure your knee does not extend past your front foot. -
(3) Single Leg Extension Variant - Turn the foot of the leg that is being worked about 30 degrees outward. Perform the extension and hold it at the top for about 2 seconds and get a good squeeze.