Welcome to the forum!
Will this be your first experience owning a horse? Based on your post, I'll (tentatively) assume that it is.
If so, don't worry about what breed to shop for. There are a lot of other qualities that take precedent over breed when choosing a first horse. I recommend shopping for temperament and experience first of all, with conformation a close third. At this point, here is a sort of "laundry list" of what I would look for in a first horse: Sane
(predictable, reliable, no major issues that have caused him to be passed from owner to owner) Quiet
(While a flightier, more nervous horse doesn't equal a bad horse, starting your ownership experience dealing with a constant bundle of nerves isn't the cup of tea of most new owners) Vice-Free
(No cribbing, weaving, pacing, etc. Steer clear of barn/buddy sour behavior, although that can develop at any time if it isn't headed off. Dealing with ingrained vices is difficult, and potentially expensive if you have to replace equipment) Not a "Project"
(Don't buy a horse that has a history of a behavior or medical condition that will need a lot of work or maintenance to bring him/her up to soundness/workability. No chronic buckers/rearers, etc., and do definitely get a prepurchase exam by your vet before the final sale to make sure that there aren't any lurking medical problems that the seller was unaware of or failed to disclose) Conformationally Correct
(Doesn't have to be perfect breeding quality, but study up on confo and be able to recognize "fatal flaws" that may affect performance and health) Some miscellaneous buying tips
- take a knowledgeable horseman with you when you go to check out a horse. Your instructor, a horsey friend who has bought and sold horses before, etc. Another set of wiser eyes can be invaluable.
GET A PREPURCHASE EXAM! No matter what your budget is, you don't want to pay the seller, get the horse home, and the next morning have him come up dead lame from something that could have been caught on the PPE. Use your own trusted vet! Don't blindly accept the sellers' vet's word, or accept a pre-printed PPE. The horse should pass the PPE to within your expectations, and have current vaccinations and test results.
Visit a prospective purchase at least twice before buying. Definitely test ride, but do have the seller "show" the horse first. If the seller won't get on the horse, or won't display any ability that the horse is advertised to have, red flags should be flying.
If you come to a point when all of the above criteria have been satisfied, and you're choosing between several "good" horses, and you still have a breed preference, then take that into consideration. When buying a horse, color is the last thing to think about. Breed is the second to last unless you are very
intent on showing a specific circuit. Thoroughbreds can do all that you listed in the OP, but so can many appendix QH's, sport-bred paints/appies, large ponies (depending on your height, of course), warmbloods, Arabs, and the million and one good crosses and grades for sale. If you're long term goal is upper-level competition, don't forget that a less-than-ideal breed can be eventually handed down to a novice and you can level up to a more suitable breed/type down the road as you gain experience.
Sorry, that got rather long, e-cookies if you read it all! Good luck in your horse search!!