The thing about a hoop/frame in a fixed position is that you need to be able to quilt in all directions. If you're doing stab stitch, which is less popular, then that should be OK. If you're doing rocking stitch, most quilters can't do that in all directions. A hand-held hoop allows you to turn the hoop whenever you need to.
Height is definitely a factor. I'm 4'11 and find that a traditional round 16" frame is a bit too big to be comfortable for me. But a 14" doesn't get quite enough quilt in it to get the tension right, I find, and you have to keep redoing the frame which I hate. I prefer Q-snaps anyway, and they're rectangular. An 11" x 17" is perfect for me to get my arms around, you get a fair bit of quilt into it, it's much easier to adjust the tension, it doesn't leave such bad creases on the fabric (if you're careful, it doesn't leave any), you can adjust it to be another size if need be (e.g. for beading), and as it's rectangular, the spaces you're quilting tile neatly across the quilt.