Maud's got a good point. I have to admit my first horse is a Greenbroke ottb, but that's what I wanted. Sometimes it's more fun to make a horse YOU want to ride than th buy someone else's ride and have to completely reteach.
Look for a horse thats between 10-14 y/o usually a horse around 14 y/o costs less cause its ‘older’ so you can’t ride it intesive for another 10 years but if you’re looking for an experienced horse i think that wouldn’t be a problem. I bought my horse when it was 15, now its 18 and it can still work intensively. So as long as you take good care of your horse, it can not be a problem