I highly suggest you hire a Professional Saddle Maker/Fitter to come out and help you in finding a saddle that is right for both your horses back, and you.
Someone can say "oh get a Thorowgood T6" but you don't know, until it is on your horses back, and you are in it.
Some horses have strait backs, some horses have more arched backs - so then some saddles are made with straiter tree's and other saddles are made with more banana shaped tree's.
TB's, like my TB can have pockets behind their shoulders. Can be A Symetrical, with broad backs and the list goes on - so you don't know what will fit your horses back without educated help.
Saddle fit is a hard thing to do. Most saddle Maker/Fitters will come out with a truck full of saddles. Tools and the educated to beable to help you find a saddle that will work great for the both of you.
My Thorowgood fits my TB like a glove, but it's a synthetic saddle which some people don't like. They make a model specifically for high wither horses. My leather saddle is a Bates. It fits well when I have the correct gullet (usually the narrowest one) in it.