If you are a recreational rider, you can follow your personal taste on this one. If you hate sweatpants, you will certainly not feel comfortable in riding leggings. However, the longer you ride in breeches or riding leggings, the more you will appreciate the comfort of riding leggings. Riding leggings are usually cheaper than breeches. In summer, the usually lighter fabric of riding leggings is more comfortable than the heavier fabric of riding breeches. On the other hand, in winter you are more likely to be comfortable wearing winter riding breeches than winter riding leggings. When it comes to competition gear, however, you should be more careful. At least for dressage competitions, riding leggings are not recommended, even if they are white. Dressage judges are very conservative. It can be a real disadvantage for you if you compete in riding leggings instead of breeches.