There is very little difference in residual sugars between yeast strains. Apple sugars are all simple and very fermentable, and the sugar content is low so there is no chance the alcohol content will max out as with wine or mead. Cidermakers trying to retain residual sweetness naturally do things contrary to yeast health in beer brewing - such as stripping out nutrients, underpitching yeast, and racking before fermentation is complete. Other than that, the only option for most is killing the yeast, sweetening, and force carbonating.
Fresh cider from down the road is the best place to start. Taste the sweet cider, the better it tastes, the better the finished product.
Some apples are better than others, but that is a complex topic and the best varieties aren't widely grown anymore. Try here for more information. http://www.ciderworkshop.com