Now that IS a question as it really depends on your time, fencing, ambitions etc.............you will get a million good answers!!!!
I am assuming you are a hand spinner if this is the case you cannot beat a good Shetland for wool quality as it spins, felts, comes in a variety of colours and also makes fantastic rugs from the lambskins which are the byproduct of its delicious meat.....
However be warned....most Shetland sheep.....not all are very flighty and can be exeedingly difficult to manage without VERY good fencing!
Down type breeds have 'bouncy' wool which is very nice, medium soft with superwash qualities!!!..........they were originally used in the hoseiry, jumper and sock industries......stuff that needed a lot of washing!!!
Thier wool is difficult to felt.
Long wools ......softish....Wensleydale, no kemp hair, worsted spinning, can be difficult to hand spin as requires combing not carding, Same for Gotlands and a few others...........very valuable lambskins!!!!
Carpet sheep.........eg Herdwick and Greyface Dartmoor....make lovely carpets, taste nice, wool like knitting fuse wire or brillo pads!!!
............use for carpets only (or have several layers underneath)
My business is wool.............so always ask!