Definitely Thoroughbreds and Thoroughbred/Warmblood crosses. Personally, I prefer the full Thoroughbreds, but I do like some of the TB/WB crosses I've ridden.
TBs just have such go to them and they really do want to please, but they can be quirky and they need to have time to figure things out or they can get incredibly frustrated. Some people don't like dealing with that, but in my opinion when you can get them to understand what you're asking they give you 200% and do the very best that they can.
"Always be yourself. Unless you can be a unicorn. Then, always be a unicorn."