A brown one specially for showing (straight cut saddle flaps) if you are doing this regularly. Otherwise a brown GP, not point in spendin £800 or show for one or two shows.
Ideal do a show saddle and a working hunter
Fylde do a very large range, show and several WH styles
Jeffries do WH
Keith Bryan do a show/wh
also Black Country, Farringtons, Barnsby, etc
Have a look on Ebay for some idea of styles and makes.