I live near King Ropes, so I'm a bit partial. They are just top-notch ropes. Check out their site. It's fun to go there and try several types. King?s Saddlery, King Ropes | Sheridan, Wyoming
I always recommend borrowing when wanting to try new gear.
Personally I go with a 3/8" scant at 40' for general roping for doctoring. Soft to extra soft. One of my best friends and favorite guys to doctor with uses extra, extra soft lay ropes at 7/16". He says it's as easy as tossing a t-shirt at the cow.
Arena ropers seem to like at least a medium lay, in my experience. Different needs.