I personally would go with a Capitol I lined stallion for her to go for the classic Cor de la Bryere- Capitol I niche (which produced Crown Affair for the U.S Hunter world.
Generally speaking, their rideability is excellent. The Abdullah in her pedigree and the fact that she has not been tested under saddle to prove her rideability would give me pause in breeding her to stallion whose lines might not produce the most rideable.
I would also look into Chaleon (by Calido I). Calido I’s will give a more fluid movement, refinement as well as typiness and rideability, although he is on the smaller side.
Also, how are her feet? I only ask because Voltaire and his sons require a mare with very correct front leg/hoof conformation. Voltaire himself had a crooked right front foot, which originally kept him from being approved as a youngster and he unfortunately has a tendency to transmit it through his offspring unless bred to a mare that throws very correct foals.