Every time I've been for a lesson or a ride I always get given anything 15.2+ (once on a HUGE just under 18hh) which has made me think that's all I should be riding! Also asked the only 2 horsey people I know who said 15.2 and above.
The larger of my two geldings (Trooper) is a 14.2/3 Appy/Arabian. He weights about 840, I weight about 175. Add 30 lbs in clothes & saddle, and we're at 205/840.
The mustang pony (Cowboy) is 13 hands on a tall day...I'd guess 650ish for weight, tops. I use an English saddle with him, and I need to pay close attention to my balance and his. His trot is like a drunk sailor, while his canter is very smooth, so we canter more than trot. If my weight bothers him, he hides it well - but I could throw him off balance if I was sloppy. Being a short wheelbase model, he can turn up his butt at speed and I need to anticipate and adjust.
Trooper & I:
Trooper is about the smallest weight horse I feel comfortable riding without restriction. I'm at 25% of his body weight every time we ride. I'm at least at 30% with Cowboy. I'd be willing to ride him for 2-3 hours at a walk, but since we canter & gallop, I keep most rides down to 30 min.
I will say that they both seem to prefer my riding to that of my youngest daughter & daughter-in-law, both of whom weigh around 100 lbs but who are not exactly fanatics about not bouncing. A rider who tries to move in synch with their horse is much better for the horse than a rider who just weighs less.
Seeing you in a Western/Stock Saddle reminds me that riding isn't so hard. British saddle is so 'proper' and I'm having to learn everything all over again!
That was a great saddle to start over in, and I'm now mad that I sold it when I lost so much weight, because this fat backside would love to have it here right now. It was an Abetta Endurance Saddle very light to carry, didn't add to much extra weight to the horses load, no horn to get in the way and make life uncomfortable, it fitted a lot of horses and they went well in it.
What I really liked is I could ride more English or western in style as I fancied. *Le Sigh* I shouldn't of sold it