The choice between full seat or knee patch riding breeches would depend on your personal preferences and your particular riding requirements. While quality full seat riding breeches give you stability at the knees, as well as the thighs and seat area, knee patch breeches allow for more freedom of movement.
When the weather is warm, you will start sweating faster while wearing full seat breeches, but on winter days they offer more protection against the cold. Your riding style should also be taken into account when choosing riding breeches. Because western riding disciplines involve a lot of movement, for instance, full seat breeches are most suitable here. You would also benefit from the extra support in the saddle and the better protection of your seat when you are on more demanding or trail rides.
For easy rides you need plenty of freedom of movement. Therefore knee patch breeches are the better choice. However, there isn't a definitive answer to this question, as preferences vary so greatly between individual riders. Some riders actually prefer breeches without a full seat as they simply feel most comfortable in them.