The type of riding you do may dictate what type of boot you wear.
Dress, Field, Paddock?
Tall riding boots give the rider lower leg protection against rubbing, and getting pinched by the stirrup leathers.
Dress boots are tall boots with no laces.
Dress boots were traditionally stiffer than field boots, but now manufacturers have made them in softer leather. The softer leather requires no break in, but will not last quite as long, or look quite as sleek as a stiffer boot.
Many dressage riders like a boot that is stiff. It gives a lot of support, as well as looking neater as it does not drop as much at the ankle as a softer boot would.
Field boots are tall boots that have laces in the ankle. The laces make them more flexible at the ankle, as well as offering room for people with high insteps. The added flexibility of the laces makes these boots great for jumping.
Boots in the past were put on with boot pulls, but now most come with zippers allowing you to get a more contoured fit at the ankle, as well as making them easier to put on.
You still need to make sure your boots fit well. They should be just to the knee, and when new, maybe a bit tall because they wrinkle at the ankle and drop. You also want them to fit snug to your leg with no gaps. Click the video link to see how to measure correctly for your new boots. https://youtu.be/w_Df7JVoAa4
Many people wear paddock boots while riding at the farm, or for lessons or camp and children need to wear them for show. Paddock boots come just above the ankle and may have a zipper or laces. Zippered boots are easier to put on, while laces give you more support and will adjust to your leg.
You may add a half chap to get the feel and protection of a tall boot.
Half chaps are a leg covering that slips on over your boots and come to your knee. They may be made from leather, suede, fake suede, neoprene, or a mesh material for summer.