Howdy! It's very nice to meet you! I'm glad you could join. I live smack in the middle of Tennessee-

If people just want to "ride western," riding in a western saddle, and learning to hold the reins in one hand lol it doesn't really matter what breed your sitting on (Well, Arabians supposedly have trouble with western saddles, and there is a specific type of western saddle designed for the arabs) you can toss a western saddle on a mustang...or a thoroughbred...

But yep there are certian breeds that tend to exell better in certian disciplines such as barrel racing, western pleasure, working cattle etc... 99% of the time you'll see a good ole' Quarter horse, or a Paint (which is "pretty much" a Quarter horse) for the cowhorses.
Western pleasure has alot of Quarter horses and Paints, barrel racing usually has the same- some people that I know like crossing up with a bit of TB for the longer, finer bone, and the height...some people just like purebred quarter horses...

In the english world, I usually see Thoroughbreds...though in such disciplines as upper-level Dressage, I see alot of Warmbloods, and thicker breeds such as the Friesian etc... TB's as far as I know, still lead the world for jumpers.

By the way I LOVEEEE Gypsy Vanners, and Cobs! I have a neighbor who lives about 25 miles from me who raises Gypsy cobs. She has about 10-12 of them.

So...welcome to the forum!