For riding, I have an old pair of Ariat ropers. Got 'em on sale for $50 about 7 years ago and they are oh, so comfortable!
For wearing around, I have several pairs of Ariat Heritage. Super comfortable. Got 2 pair of mine off Ebay for cheap, and they were brand new with tags, or worn a few times.
I think it really depends on the individual horse, and it's conformation. I had a 15.3 gelding. He had a very long, animated stride. I didn't realize how hard he was to sit until a friend of mine got on him. She was all over the saddle!
KellyG and Lupinefarm, Beautiful horses! I really love the Haflinger and Fjords. I ride a Foxtrotter/draft cross that belongs to my neighbor, and just love him. If I ever get another horse of my own, it will be a draft cross.
Ps I've also ridden a percheron and clydesdale and loved it!