Im the opposite to you have tried the manta rays and settled for prowler 13 and am very happy so I suggest you try and paddle a few before you buyI am about the same size as you, maybe a stone heavier. I have a Manta Ray 12 and a Manta Ray 14.
The 12 is better when fishing in confined areas as it is more manoeuvrable, whereas the 14 is better in open water and is a little faster. (I am not a kayak snob, my son uses the 12 most of the time, but I pinch it when he is at school and I want to fish around tight gulleys. I would recommend them both and prefer them to a Prowler 13 that I have paddled previously.
LINKEY