Partly a financial question: nursery was more than we could afford.
But also, I wanted dc to be in a home atmosphere, where they would be taken around the local community and be part of an everyday home routine. Taking older children to school or even popping round the local shops for the occasional item was something I saw as a positive learning experience. It is a trust issue, but the CM we went for had a very good reputation built up over many years.
I'd say my expectations were more than met: dc grew up knowing far more people in our local community than I ever did, they attended craft clubs and other events with their CM, and I always felt they were safer with her than they were with me, as she was undeniably better trained and more experienced. They did all sorts of little projects round feast days from different cultures etc- very much the same sort of stuff they do at nursery. They also attended play school twice a week, so they did get used to the pre-school routine. And when they started school, they were already familiar with the school ground and the older children because they had been taken there daily for years- just like they would have been with an older sibling. And there were older children there who knew them and looked out for them.
Never any problems with illness, and there was a very well organised, very transparent system of cover between local childminders so you would never be left stranded if your own was ill or if there was an emergency. Always felt very safe with that aspect too, because it was so thought-through and organised.
In the end, we ended up using three different childminders, but that was purely for logistic reasons: we were satisfied with all three of them.