TBs
I don't know very much abiout endurance except, as you said, that arabs are great for it. I would think that a TB would not be as good at endurance, but I don't know for sure. TBs aren't as "hardy" as arabs, who are known for being able to travel in heat and go without water for longer than most horses. Also, the structure of arabs is more conducive to hard and long riding. TBs are fast and I love them, but I don't know if I would use one for an endurance horse. But take into account that this is just an oopinion- I don't know enough about the sport to say for sure.
Anyone else out there have an idea?