Most people start a service contract search with the cost of a repair. A second question is often more useful: when the unit stops, how long would the household go without it, and who would come? Those answers decide whether a contract solves a real problem or only a paperwork one.
Start with the unit's role. A refrigerator holding food for a household that shops once a week is a different matter from one where a freezer is the only backup. Write down what the household would lose on the day the unit fails: heat, cooling, water, a way to cook, or a way to get around. Then write down how long that loss could last with no one available to fix it.
Next, list the people who could arrange a repair. Some households have a neighbor or relative who knows the trade. Some live far from a qualified shop, or have no one home during working hours. Some rent, and the landlord holds the repair duty under the lease. Each of these changes what a contract adds. A contract may give a route to a repair person the household would not otherwise find, but it does not change the distance, the hours, or the landlord's duty. Read the lease and any existing home warranty before you assume a new contract fills the gap.
Ask the seller or provider these questions in writing. Who dispatches a technician, and how is the visit scheduled? What hours does the provider cover? Does the provider use its own staff or independent shops? If the household lives outside the usual service area, does the contract still apply? If an answer is given as a general tendency, ask again until it is stated as a term of the contract.
Finally, compare the access you have now with the access the contract would add. If the household already has a trade contact who reliably answers the phone, a contract may add little for that unit. If the household would be left waiting for days with no heat or cooling and no one to call, the access question is the one to settle first. The state page on this site names who regulates these contracts in each state and says whether that state publishes a roster. Where a page says the state has not been read in this edition, check the state's own statute and the list's as-of date before you rely on anything.