I didn't read all of it, but I say find a horse that can do what you want it to do and well. Really, I wouldn't pick and prod at breeds. Its harder to find a horse that way. Say you find a TB that can do what you want and more, but you want a Warmblood. It would be best that you go for the TB but you settle for a less trained Warmblood. Later on you might regret it, just because you had to have a warmblood.
I see alot of people get horses they regret getting because the other horses that did what they wanted even more, but settled for another because they did like the one horse's color, breed, ect.
That's just my opinion on it.
But if you want to show a breed show that's another story But we wont go there.