I just gave up a lease on an OTTB because she was 100% bombproof, kid-safe, perfect level-headed hunter mount at five years old
. I ended up buying an Appendix who had the spice and fire I was looking for
Honestly, most OTTB's with the proper retraining are going to be amazing mounts, the only thing you have to look out for is that they weren't thrown right into under saddle training the second they came off the track, it's not usually case, but it does happen- and then get them thoroughly checked over by the vet to make sure there's no injuries. TB's are amazing horses, if you can afford to feed them.