What is your mare's breeding??
The size of the stallion has little bearing on the size of the foal in the womb, it will only grow as big as the mare lets it (is what I have heard at least).
Which stallion to breed to depends on the lineage of your mare. You might want to look into Dancier as another Donnerhall stud with good offspring and I would highly recommend a Florestan stallion, Freestyle is a very good choice (assuming you are in NA).
I would recommend also breeding more towards a very ridable horse than something with fancy movement. Freestyle's offspring are proving to be very amateur friendly, but still with movement and power to win in the ring.
They say money doesn't buy happiness -- well happiness doesn't buy horses!