Tried a Dakota brand saddle on my QH last year, seat seemed to me to be hard as a brick. Person selling it said his horse was having back issues. Not sure if it was the saddle.
I just bought a Cashel western saddle, made in the USA by Martin Saddlery. Fits my horse well, seat is soft and cushy. HUGE bonus, it only weighs 25 lbs!! They are over $1,500.00 new, scored mine off ebay for quite a bit less.