My eye with ptosis is prettier? How to balance?

Based on your photos, you have asymmetric ptosis, left worse than right. Its important to have your eyes evaluated by an Oculofacial Plastic Surgeon (Oculoplastics) who can evaluate you and show you what the goals of the surgery should be. There is a test we can do in the office that would show you what you might look like after a ptosis repair. This test will possibly unmask the droop on the other side. 

"Squint" is a lay term for strabismus. Strabismus refers to eye muscle that don't align. The eyes together see double and this visual confusion is dealt with by closing an eye. That is not what you have. You have ptosis but it is not just your left eye. It is both eyes. It is just that the left eye is a bit worse. If one were simply to correct the left side, the right eye would look heavier than before surgery. That is called Herring's law ptosis. The fix is addressing both eyes at the same time. You have a thin upper eyelid that reflects a central disinsertion of the levator aponeurosis. Correcting the upper eyelid will allow the eyebrow to relax down. Right now, you have a compensatory eyebrow elevation which contributes to the hollow upper eyelid sulcus. When the eyebrow relaxes, it will help make this area less hollow, emphasizing the almond shape of the eye. This does require a detailed personal assessment and surgery. Surgery is comfortable performed under light intravenous sedation. Recovery is relatively rapid. Your eyes can be your best feature.