All three of those longwools come in colours as well as white. In fact I think nearly all of the longwools do. I can’t think I’ve heard of coloured Cotswold or Teeswater but I have spun, seen or heard of coloured BFL (Blue-faced Leicester), Leicester Longwool, Lincoln Longwool, Romney, Wensleydale.
If you’re a spinner, Leicester is the softest of all the longwools. Lincoln has a beautiful lustre, and a strength like no other longwool, in my opinion. I like to use 2 plies of Blue-faced Leicester and one of Lincoln in my sock yarns. I wouldn’t use Leicester for strength in sock yarn, although I might use it for softness with something else for more strength.
Apologies if this was ambiguous. In common with most spinners, I always say Blue-faced Leicester in full, or type the abbreviation BFL, so when I say “Leicester” I mean Leicester Longwool.
So to retype it unambiguously...
If you’re a spinner, Leicester Longwool is the softest of all the longwools. Lincoln Longwool has a beautiful lustre, and a strength like no other longwool, in my opinion. I like to use 2 plies of Blue-faced Leicester and one of Lincoln Longwool in my sock yarns. I wouldn’t use Leicester Longwool for strength in sock yarn, although I might use it for softness with something else for more strength.
Reading the RBST pages about the two breeds would put me off the Leicester Longwool. Or at least, if I had them, I’d cull hard for any lambs - and mothers and fathers of lambs - that are “slow to get going”. Not a trait I’d want in my flock.
Sorry for any confusion.
As to knitting yarn for yourselves, will you be doing the prep yourselves or getting the yarn made for you? And what sort of garments are you wanting to knit?
As spinners we say that BFL is a dream to spin and a nightmare to prep. Both Lincoln and Leicester Longwool are generally far easier to prep (wash, comb, card; gettting the fleece ready to spin) than BFL, although there are exceptions of course.
Lustre-wise, Lincoln is usually very very lustrous, BFL very lustrous and can be extremely so, Leicester Longwool slightly less lustrous than the other two. Softness-wise, Leicester Longwool is reputedly the softest of all the longwools, BFL next, and Lincoln less so. Again there are of course exceptions. One of the most delicious fibres I’ve ever handled was a silver Lincoln Longwool shearling. It was so lustrous it looked like actual polished silver, and as soft as a lustrous yarn can be. (To be highly lustrous, the yarn needs to be not fluffy. The softer fibres are often slightly fluffy, so in general, less lustrous.)
If you want yarn that will be lustrous and or give you fantastic stitch definition (eg for cables), then you want the less fluffy ones, and you want the yarn to be worsted-spun, which means the fibre is combed rather than carded and the yarn will be more dense.
If you want soft and fluffy, then you’d go for less lustre, softer fibre, a carded prep and a woollen-spun yarn. The yarn is light and airy, warm for its weight, but has less lustre and the stitch definition is poorer.