It is a personal thing, but it seems to me that good looking breeches require boots with two important characteristics - they must be the right height and fit snugly at the top.  For me, this means a boot about 17 to 20 inches tall fitting shugly just below the knee.  Above is one of my favorites - an Ariat riding boot about 20-inches tall.  It has a laced instep which makes it comfortable for walking, and a toe cap which takes a good polish.

Below is another pair of boots which I think of as being the appropriate height.  They are Wesco Boss boots, 18-inches tall, leather lined.  The breeches are a style called "drop front".  A button flap is used rather than the customary button or zipped fly.