Difficult to say, other than that for size Shetlands are good as they are not massively big sheep, and I can easily deal with any of them on my own, the ewes weigh about 40 to 45kgs, the boys would be a bit heavier, my tup would probably be in the 55kg region.
Any young wether/ewe can be trained to the bucket fairly quickly, but they can become quite boisterous if they see you with it.... mine go mad for the orange B&Q bucket.
Actually a couple of older ewes (again Shetlands would be good for this, they can live happily to 13 or 14 years) that are at the end of their breeding life, but come from a small flock would be ok. You don't have to breed from them, and they do not become noisy (like goats) when in season.
But you have to be prepared to feet trimming, dagging backends, shearing them (or knowing someone who would come and do them for you), possibly they will need worming/fluke treatment, maintaining their vaccination status and/or giving other injections/drenches. Also knowing how to check for and deal with flystrike is quite important. You will also need to get a CPH and a flock number, and register with a vet.
But tame sheep are a joy, my two favourite ladies were Shetlands that came to me when 9 and 10 years old, they would come to you when you rustled a plastic bag, as their previous owner used to bring them toast in it...