My neighbours over the hill who are getting on in years switched to Lleyns a few years back and they absolutely love them. Plenty of lambs, good mums, grow on grass. They have 300 ish and only had to pull two this year.
I only don't have them as I am lazy so only want one or two lambs so i dont have any bottle lambs from triplets or quads but the Lleyns are about the best and easiest of the prolific breeds, I think. My vet has them too. Smart looking as well.