sheep are so different i think you need to choose what character suits you, and also your land, and fencing.
for example. i personally dont like handling huge sheep, or ones that jump fences like deer, and as id like to learn to spin one day, a soft fleece is a plus. if you are working with them everyday, it helps to actually like them, whether its business or hobby.
have a look at the rbst website and see what you fancy, see what they sell for, what the demand is etc
sometimes rare breeds are so rare people dont know what they are so dont bid for them, and also cant source unrelated stock to breed pure.
i always like balwens but couldnt find a ram anywhere for the 2 girls i had.