There are 4 heights in boots: Over the knee, under the knee, at the calf or an ankle bootie. All are equally flattering if it fits your body type. But the key would there is: body type! I truly believe that over the knee and at the calf are the hardest to wear boot. I think for both these styles you have to be extremely tall and thin. These boots cut you at a place that accentuates curves. That's not necessarily a bad thing if you don't have curves, but honestly, unless I look like Giselle I won't be wearing these styles.
The boots worn at the knee and ankles booties, I think are the most forgiving, and honestly, the most classic. I know some of you are saying "ankles booties", "they make my butt look big". But the booties are very versatile. Pulling your jean over the boot gives you a streamline leg. Also wearing a heeled bootie with leggings and a longer tunic or even a dress gives you a proportion that's pleasing to the eye.
Boots to the knee are the most classic. Whether you like it heeled or flat, you really can't go wrong with a boot to the knee. The only thing I think to watch out for is the size of the opening at the knee. If it's too big, it looks sloppy. I also watch for the proportions of the articles of clothing I'm wearing. If worn with a jacket at the waist, I like a longer tunic underneath. If I'm wearing a shorter top, a longer cardigan looks modern and chic.
Regardless of what you choose, just remember to be you. Being you is your greatest accessory. xoxo