Personally I wouldn't have chosen either one of those, but regardless, it depends on the horse. I've know very hot thoroughbreds and I've know very calm ones. Clydesdales are quite large and a little bit more difficult to manage as they have feathers and larger hooves. I would really recommend a Quarter Horse or similar stock breed, but if you have your heart set on a TB or Clydesdale, look around at some TBs first. TB/QH crosses (called Appendix Quarter Horses) are actually fantastic for general riding purposes.
It depends on the horse. Personally I like TBs but for a leasure horse a Clydstale MIGHT be better. You should check uot many horses and see their personality. But yes, TBs can be quite hot but I really think it depends on the horse.