Depending on your needs, depends on what type of dog you may require.
Perhaps a smaller breed would work for you in assisting with picking up items that you drop and can not reach. Turning lights on and off, bringing you the phone or other items. Capable of getting on the furniture or your lap to make it easy for you to reach.
Or maybe you need a larger breed that can brace in helping you to get from a sitting to standing position or standing to sitting position. To help prevent falling, assist in walking or pulling and pushing a wheelchair. Open and close doors or help take off your shoes and socks. Picking up larger items like crutches or bringing your wheelchair to you.
All breeds can be trained to do all of the above and more, with the exceptions of wheelchair assists and bracing which the larger breeds are best for.
Be sure to pick a companion that has the capabilities that you require and will not put undo pressure or strain on the dog.
