Everyone will tell you something different as all have preference for their own breed.....I have kept lots of different breeds over 30 years and can say with confidence.....
Start by deciding if you want meat AND wool.....some of us really like wool
and can make lots of things from it!
Take a look once decided at the fences on your fields.....are they very good and strong or a bit you know what
Then try a few lambs for the freezer and see if you actually like sheep!
Then decide!
Oh and get as much experience with other peoples flocks as you can in the area!
A lot of stress and heartache, not to mention welfare issues will be avoided like this!