What is best medical alert system for me?

I am in a wheelchair with a spinal cord injury. My balance isn't good. I have lengths of time when my husband leaves, and I worry about falling though I am cautious. Several people have suggested a medical alert system so I can get help if I do fall, but I feel overwhelmed by the many options and plans when I research the various companies and plans. Is there such a thing as a good, yet basic system? Can anyone help? thanks