I thought I wanted a tall horse 16.2+ build didn't matter, I just wanted the height.
I found some tall horses, both really stocky and quite narrow, but I either felt uncomfortable or was afraid of falling off (long way down)
My horses are between 15-15.3 and I'm very comfortable with them all. I like a medium stocky-stocky qh build. I would chose a 15hh horse over a 16hh horse any day.