Well I was 5'6" last time I checked. My horses are 14.3hh, 15hh and 15.3hh. I feel comfortable on all of them. The tallest and shortest are both narrow but my 15hh boy is quite wide in the barrel. I have ridden horses as small as 11 hands. I don't mind going that small, I just find it more difficult to give them leg aids because my legs are too long. I like horses in the height range of what I have.
Both my girls are a little over 14hh and stocky. I'm 5'4" & have had a few to many groceries. I think were a good fit.
I wouldn't want to ride anything taller than 15hh. I used to lease a 16hh gelding. It was hard as heck getting on and off of him. The smallest horse I've rode was a friend's 14hh Arab. She was really narrow and had a short back. I felt huge on her.
I am 5'7 I can ride 14.1 pony's, and FEEL comfortable(I have long thighs and short calf's, it is funny!) but I look best on horses about 16hh(or a bit bigger). I ride one who has a small barrel, and one who has a big one, feel comfortable either way. Getting the right length stirrup is a challenge though :/
Actually I lied, when jumping pony's I feel funny because of short necks.
Lottie is 15"2 and I feel completely comfortable on her because she's not narrow. Because I have long thighs and calves, my flatwork stirrups are really long but my jumping stirrups are really short, it helps me keep my balance although I do feel like a giraffe with my legs all folded up!
I'm 5'4" and the smallest horse I ride is somewhere in the neighborhood of 15.2 hands and the largest is an OTTB who has to be pretty darn close 18 hands. His size was scary at first but now im totally used to it!